cognate: Two words (or other structures) in related languages are cognate if they come from the same original word (or other structure). Generally cognates will have similar, though often not identical, phonological and semantic structures (sounds and meanings). For instance, Latin "tu", Spanish "", Greek "", German "du", and English "thou" are all cognates; all mean 'second person singular', but they differ in form and in whether they mean specifically 'familiar' (non-honorific). [Spanish: cognado]