There are many words that are cognates in Sanskrit and Tamil, in both tatsama and tadbhava forms. This is an illustrative list of Tamil words of Indo-Aryan origin, classified based on type of borrowing. The words are transliterated according to IAST system. All words have been referenced with the Madras University Tamil Lexicon, which is used as the most authoritative and standard lexicon by mainstream scholars.[3][4] In the examples below, the second word is from Tamil, and its original Indo-Aryan source is placed to the left.
^Another source asserting the status of the Madras University Lexicon is this page where it is called "still the most comprehensive and authoritative Tamil dictionary."
S Vaidyanathan, Indo-Aryan loanwords in old Tamil, Rajan Publishers (1971), ASIN B0000CQQI3 [2]
Chandran Tucker, A dictionary of English loan-words in modern Tamil: Contributions towards a modern Tamil-English dictionary , Biblia Impex (1986), ISBN81-85012-14-8
R Wallden, Hidden Indo-European and/or Indo-Aryan "Loanwords" in Old Tamil?, Orientalia Suecana Uppsala 1980, vol. 29, pp. 140–156 - [3]