answer:No. I just had this discussion in terms of the etymology and linguistic context – it isn’t cut and dry, black and white, however; I proposed that bitter is to sweet, as up is to down. Tart, being a negative sensation on the tongue – especially for babies, and then, psycho-tastewise (coining a stupid term, here – for lack of any real knowledge) one learns to like, or dislike something tart. A lemon isn’t tasty on the tongue. It’s tart, and sometimes bitter. Sour is also good for a lemon olfactory description, but sweet and sour compliment each other – like the chinese sauce. Thus, bitter is the opposite of sweet, imho. Tart is unpleasant, naturally, however one may have acquired a taste for it – like for olives and caviar.