couth
‘known, well-known; usual, customary’
Lexical development traced from the Tamil root:
E. cúþ, kuð, cowþe, kowth < M.E. couth ‘known, well-known; usual, customary’ < O.E. cuðe ‘known’ < cunnan ‘to be able’ < Proto-G. kunnjanan ‘be mentally able, have learned’ < kooth < gno- < Tamil kaṇ