【Bitter】 , 【acrid】 are applied to things with an unpleasant taste (also smell, in the case of 【acrid】 ) that is neither sweet nor bland yet seldom distinctly sour or really sickening.
【Bitter】 is traditionally associated with the repellent taste of wormwood, quinine, and aloes, but it is also used to describe the taste of beer, unsweetened chocolate, and the rind of citrus fruits. Something 【bitter】 usually lacks the pleasant tang and freshness of an acid flavor (as of lemon juice) and has a penetrating and persistent quality difficult to mask.
【Acrid】 implies a bitterness in taste that has an astringent or irritating effect (as the taste of chokecherries, various unripe fruits, or alum). It is also applied to something both 【bitter】 and salty (as sweat).
An 【acrid】 smell is a penetrating, suffocating, repugnant odor. It is especially associated with certain fumes (as from burning sulphur) or with certain noxious vapors (as of a heavy city fog).
