sour on

:  causing or characterized by the one of the four basic taste sensations that is produced chiefly by acids — compare bitter, salt, sweet

:  having the acid taste or smell of or as if of fermentation :  turned

:  of or relating to fermentation

:  something sour

:  the primary taste sensation produced by acid stimuli

:  a cocktail consisting of a liquor (such as whiskey), lemon or lime juice, sugar, and sometimes ice

:  to become sour

:  to make sour