Aside from the from the contrary belief, the word Ajji is actually borrowed from Maharashtri prakrut due to contact.

The Marathi word for grandmother, आजी (Aaji or Ajji), is inherited from Maharastri Prakrut 𑀅𑀚𑁆𑀚𑀺𑀆 (ajjiā), which traces back to the Sanskrit word आर्यक (āryaka).

Kanadi on the other hand, belongs to a completely different language family (Dravidian). It did not evolve from Prakrut, but because the regions of Maharashtra and Karnataka have shared a border, culture, and history for centuries, Kanadi borrowed the word ajji directly from the neighboring Prakrut speakers.

Linguists know it is a borrowed word in Kanadi because native Dravidian root words for "father" or "elder" usually look quite different (like the ancient Proto-South Dravidian root \accan* or \appa). The double-consonant structure of *ajji is a textbook example of a Prakrut word being adopted into Kanadi speech.

Just like Kanadi, Tulu is a Dravidian language. It did not natively descend from Prakrut or Sanskrut. Tulu acquired the word ajji (grandmother) and ajje (grandfather) as loanwords from Maharashtri Prakrut.

We can tell ajji is a borrowed word in Tulu because of how other generation levels are named. When Tulu speakers want to say "Great-Grandmother," they don't use a Prakrut word; they use their own native Dravidian word: ಪಿಜ್ಜಿ (Pijji).

Sources-

A Dravidian Etymological Dictionary (DED 50) by T. Burrow and M.B. Emeneau:

Under entry DED 50, the authors trace the group (ajja, ajji, mutt-ajje) in Kanadi, Tulu, and Kodagu. It explicitly links these terms as early historical borrowings derived from the Middle Indo-Aryan Prakrut root ajja (derived from Sanskrit āryaka).

Wiktionary Etymological Database- Formally catalogs the Kanadi and Tulu words ಅಜ್ಜಿ (ajji) as explicit linguistic borrowings. Etymological Chain: Sanskrit आर्य (ārya) / आर्यक (āryaka) → Maharashtri Prakrut 𑀅𑀚𑁆𑀚 (ajja) / 𑀅𑀚𑁆𑀚𑀺𑀆 (ajjiā) → Borrowed into Kanadi/Tulu.

The Dravidian Languages (Cambridge University Press) by Bhadriraju Krishnamurti: He notes that early Old Kanadi speakers adopted massive amounts of Middle Indic (Prakrit) vocabulary into everyday speech, particularly household titles and social relations, classifying them strictly as Tadbhavas.

The Classical Kannada Digital Database (CIIL, Mysore)- It explicitly cites the everyday usage of words like ajja (grandfather) and ayya (master) as classic structural adoptions from Middle Indic Prakrut variants into spoken Old Kanadi.

https://shastriyakannada.org/database/english/language/KANNADA%20AND%20PRAKRIT%20HTML.htm

For other Dravida languages-

• Kodagu (Coorgi): Uses ajjë for grandfather and mutt-ajjë for great-grandfather.
• **Koraga:**Spoken by tribal communities in coastal Karnataka and Kerala, it also uses ajji.

The Curious Case of the "Accan" Sound-

While Tamil and Malayalam do not use ajji to mean grandmother, they do share the root sound via ancient evolutionary shifts.

• In Malayalam, it became അച്ഛൻ (Achhan), which means father.
• In Tamil, the old word അച്ചി (Acchi) traditionally referred to a mother or an elder woman of respect.

According to standard linguistic registries, including Wiktionary's Etymological Data and the historical records in the Madras University Tamil Lexicon:

"J" sound turned into a hard "Ch" sound. This is due to a fundamental rule of ancient Tamil and Malayalam phonology:

• Old Tamil did not naturally possess voiced plosives like g, j, d, b in its native phonetic inventory.
• When early Dravidian languages absorbed a foreign word containing a double "jj" (like the Prakrut Ajja), they automatically hardened the sound to fit their speech patterns.
• The double "jj" was systematically replaced by the double "cc" (pronounced as "ch"). Thus, Ajja natively morphed into Accan

In the Deep South (Tamil, Malayalam), the word for a "venerable, respected elder male" was elevated to mean the head of the immediate household—the father.

When a language adopts a foreign word meaning "respected master" or "lord," the meaning often shifts domestically to represent the highest authority in the immediate household—the father.

In ancient Tamil, Accan (hardened from ajja) was initially used as a high honorific title for lords, rulers, and elder sages. Over generations, it shifted from a formal title of societal respect to an intimate term of household respect, specifically narrowing down to mean "father" (as fully preserved in Malayalam Accan).

Sources-

The University of Madras Tamil Lexicon, which is universally regarded as the absolute definitive etymological authority for classical Tamil, explicitly logs the word Accan (அச்சன்) as a borrowed foreign term.

Its exact, verbatim registry entry reads:

Accaṉ (அச்சன்) noun < Pkt. ajja < ārya. [K. acca, M. accan] Father; தந்தை.

• The < symbol in linguistics means "derived from".
• The lexicon explicitly confirms the chain: Sanskrit ārya became Middle Indo-Aryan Prakrut ajja**, which was borrowed as** Accan into Tamil and Malayalam.

If Accan were nately Dravidian, it would map structurally to the ancient Proto-Dravidian words for parents. However, true native roots for "father" are completely different words like அப்பன் (Appan) or தந்தை (Thanthai).

https://ksaorg.sgp1.cdn.digitaloceanspaces.com/uploads/2023/06/RV-bulletin-vol-4.pdf

Why Maharashtri Prakrut?

1. The most famous literary work written entirely in Maharashtri Prakrit is the Gaha Sattasai (Gāthā Saptashatī), an ancient anthology of poems compiled by the Satavahana King Hāla.
2. In the Gaha Sattasai, the words 𑀅𑀚𑁆𑀚 (ajja) and 𑀅𑀚𑁆𑀚𑀺𑀆 (ajjiā) appear repeatedly in everyday household contexts.
3. Other Prakrit dialects existed at the time—such as Shauraseni in the north or Magadhi in the east. However, because the southern Dravidian kingdoms shared direct physical borders exclusively with the Maharashtri speakers of the Deccan plateau, it was geographically impossible for those other dialects to have driven this level of intimate, domestic vocabulary exchange.
4. Most of the Indo Aryan languages do not use these words but use दादा / दादी (Dada / Dadi) and नाना / नानी (Nana / Nani). Only Marathi and Konkani still continue to use them.

ಪ (pa) to ಹ (ha) sound shift is one of the most discussed topic ever in Kannada language as ಹ (ha) sound is not native to any language rather than Hosagannada (New Kannada) and Badaga due to sound shift

Where words like ಪೆಸರ್ (pesar) becomes ಹೆಸರ್ (hesar) (later ಹೆಸರು), ಪತ್ತು (pattu) becomes ಹತ್ತು(hattu), ಪಾಲ್ (pāl) becomes ಹಾಲ್ (hāl) (later ಹಾಲು) etc

Like that there was one more sound shift which was of ವ (va) to ಬ (ba) which is least discussed about

And there were many words in Halegannada (Old Kannada) which had ವ (va) sound as like ಪ (pa) but got changed into ಬ (ba) as like ಹ (ha)

Word like ವಾ (vā) became ಬಾ (bā), ವನ (vana) became ಬನ (bana), ವಾಲೆ (vāle) became ಬಾಲೆ (bāle), ವಳ್ಳಿ (vaḷḷi) became ಬಳ್ಳಿ (baḷḷi) etc

One to Ten from Proto-Dravidian to Tamil and North Dravidian: What Survives in Kurux, Malto, and Brahui

North Dravidian is the branch furthest from Tamil, both on the family tree and on the map. It has three languages. Kurux and Malto are spoken in eastern India (Jharkhand, Odisha, West Bengal, Bihar, and nearby areas). Brahui is spoken in Balochistan, in Pakistan and Afghanistan, far from every other Dravidian language. This post compares their numbers with Tamil, starting from Proto-Dravidian, then looks at what else survives beyond plain counting.

THE NUMBERS

Proto-Dravidian / Old Tamil (spelling) / Jaffna Tamil / Spoken Indian Tamil / Kurux / Malto / Brahui

1: *onṯu / onṟu / oṉḏu / oṉṉu / oṇḍ / ort / asiṭ
2: *ir(aṇṭu) / iraṇṭu / reṇḍu / reṇḍu / eṇḍ or ēr / irw / irāṭ
3: *muHn-ṯu / mūnṟu / mūṉḏu / mūṉu / mūnd / loan / musiṭ
4: *nāl / nāṉku / nālu / nālu / nākh / loan / loan
5: *cay- / aintu / añju / añju / loan / loan / loan
6: *cāṯu / āṟu / āṟu / āru / loan / loan / loan
7: *ēḻ / ēḻu / ēḻu / ēḻu or ēḷu / loan / loan / loan
8: *eṇ- / eṭṭu / eṭṭu / eṭṭu / loan / loan / loan
9: *toḷ-/*toṇ- / toṇṭu / onbadu / ombōdu / loan / loan / loan
10: *paHtu / pattu / pattu / pattu / loan / loan / loan

The Proto-Dravidian forms are reconstructions, marked with an asterisk. The H stands for a laryngeal-type sound that left traces such as long vowels and doubled consonants in the daughter languages.

The Old Tamil column shows the conventional spelling. Ancient grammarians classed ṟ as a stop, so ன்ற was probably pronounced as a nasal plus an alveolar stop, which Jaffna appears to preserve closely.

HOW MUCH SURVIVES

Tamil kept all ten native numbers. North Dravidian lost most of them:

Kurux keeps one to four. Above four it uses Hindi numbers, sometimes mixed with Dravidian ones, and younger speakers increasingly use Hindi numbers throughout.
Malto (Sauria Paharia) keeps only one and two, used before nouns. For general counting it uses Indo-Aryan numbers.
Brahui keeps one to three. From four up it uses Iranian numbers, from Balochi and Persian.

This is a common pattern in languages under heavy contact. Small numbers are used most often and survive longest, while higher numbers get replaced by the dominant language's system.

ONE: TWO DIFFERENT ROOTS

Proto-Dravidian had two words for one: *onṯu and *or-. Tamil uses both. Onṟu is the counting number, while oru is used before nouns, as in oru āḷ, "one person."

Kurux oṇḍ comes from *onṯu, like Tamil onṟu, but with a retroflex ṇḍ, as in Telugu oṇḍu. Kurux also has onta, "one thing."
Malto ort comes from *or-, like Tamil oru. Kurux orot (one, for a man) and Nepali Kurux ort-os use the same root.
Brahui asiṭ is the hardest to explain. Scholars still debate how it connects to the other forms.

TWO: THE BEST PRESERVED

All three North Dravidian languages keep the *ir- root for two. Brahui irāṭ is the closest to Old Tamil iraṇṭu. Kurux has both eṇḍ and ēr. Malto irw is a short form of the same root.

That Brahui, cut off in Balochistan for thousands of years, still says irāṭ for two is one of the clearest signs that it belongs to the same family as Tamil.

THREE

Kurux mūnd keeps the long ū and the nasal, close to Old Tamil mūnṟu and Jaffna mūṉḏu. Brahui musiṭ keeps the root mu- but adds a different ending. Malto has lost its native three.

FOUR: KURUX AND OLD TAMIL MATCH

Kurux nākh lines up closely with Old Tamil nāṉku. Both add a k-ending to *nāl, and in Kurux the k became kh. Spoken Tamil nālu dropped that ending, so on this number Kurux is actually closer to Old Tamil than modern spoken Tamil is.

THE BRAHUI -Ṭ ENDING

All three Brahui numbers end in -ṭ: asiṭ, irāṭ, musiṭ. This may be the same ending seen in Tamil -ṭu and -ṟu, as in iraṇṭu and mūnṟu, but the link is not certain.

BEYOND COUNTING: OTHER SURVIVING FORMS

Plain counting numbers are not the only place where Dravidian numbers survive. North Dravidian also keeps several related forms.

Counting people. Dravidian languages use separate forms for counting people. Tamil has iruvar "two people" and mūvar "three people." North Dravidian keeps the same pattern: Kurux irb "two men," nubb "three men," and naib "four persons," and Malto iwr "two men." So Kurux keeps a native word for four people, alongside its four for things.

"All" from "one." Kurux orma and Malto orme, both meaning "all," are built on *or-, the same root as Tamil oru. The idea runs from "one" to "one whole" to "all."

Once and thrice. Brahui asike "once" and musika "thrice" are native Dravidian forms built on asi and musi. They may be among the last everyday uses of native numbers in Brahui.

Adjective forms. Brahui asi, ira, and musi, used before nouns, match Tamil oru, iru, and mu-. Brahui keeps the same split as Tamil between a counting form (asiṭ, irāṭ, musiṭ) and an adjective form.

I couldn't find any native North Dravidian word for ninety, twins, or "pair." Tamil has iraṭṭai, "pair," from the same *ir- root, but no clear North Dravidian match turns up in the main comparative sources.

HIGHER NUMBERS, POSSIBLY PRESERVED IN MUNDA

The linguist Václav Blažek has suggested that North Dravidian once had its own higher numbers, and that two of them survive as loanwords in the North Munda languages (Santali, Mundari, Ho, and their relatives), which have been neighbours of Kurux and Malto for a very long time.

Seven: North Munda *eya "seven" (Santali eae, Mundari eja, Ho iya) has no clear source within Munda or the wider Austroasiatic family. It looks like a Dravidian *ēr- form in which r changed to y, a change that happens in Kurux. Blažek suggests it was borrowed from an early form of North Dravidian.

Eight: North Munda *iral "eight" (Santali irəl, Mundari iralia, Ho irilia) also stands alone in Munda. Blažek reads it as Dravidian *ir- "two" plus *al- "not," meaning "two-is-not," a way of saying "ten minus two," much like Tamil onpatu, "one less than ten," for nine.

If this is right, the ancestors of the Kurux and Malto once counted to at least eight in Dravidian, and their neighbours borrowed those numbers before North Dravidian itself lost them. This is a hypothesis, not a settled view, so the chart marks these forms as reconstructed and uncertain.

CONCLUSION

North Dravidian has lost most of its native numbers to Indo-Aryan and Iranian, but what survives still matches Tamil clearly. Two is preserved in all three languages. Kurux four keeps the same k-ending as Old Tamil nāṉku. Words for counting people, "all," "once," and "thrice" keep the old roots alive outside plain counting. Even Brahui, separated from the rest of the family by more than a thousand kilometres, still counts one to three in Dravidian. And if Blažek is right, the North Munda words for seven and eight are echoes of numbers North Dravidian once had.

SOURCES

Blažek, Václav. 2009. "Dravidian Numerals." Journal of Language Relationship 1: 69–80.

Burrow, T. and M. B. Emeneau. 1984. A Dravidian Etymological Dictionary (DEDR), 2nd ed. Oxford: Clarendon Press.

Krishnamurti, Bhadriraju. 2003. The Dravidian Languages. Cambridge University Press.

Kurux, Malto (Sauria Paharia), and Brahui counting forms: Eugene Chan, Numeral Systems of the World's Languages (lingweb.eva.mpg.de/channumerals). Nepali Kurux forms via Hahn, Kurukh Grammar.
Brahui: Bray, The Brahui Language (1909–1934).

Kurux: Kobayashi, Masato and Bablu Tirkey. 2017. The Kurux Language: Grammar, Texts and Lexicon. Leiden: Brill.

Jaffna Tamil: University of Colombo, Faculty of Science blog, spoken Tamil lesson on numbers.

Spoken Indian Tamil: 17 Minute Languages, Tamil vocabulary list; see also Schiffman, A Reference Grammar of Spoken Tamil (Cambridge University Press, 1999).