Going from Thai to Tamil (เฎคเฎฎเฎฟเฎดเฏ) has a composite linguistic distance of 88% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Thai โ Tamil
Tai-Kadai โ Dravidian
The 5 languages with the lowest linguistic distance from Thai:
A quick 3-question check between Thai and Tamil. No signup.