means Having a sharp, pleasantly biting flavor or smell — the bright sourness of citrus, vinegar, or a good cheese.

from From 'tang,' originally the pointed end of a knife or tool that's driven into the handle — the part with a sharp 'prong.' That sense of a piercing point came into English from Old Norse 'tangi' (a spike or projecting bit), a relative of the word behind 'tongs.' Over time 'tang' drifted from a literal sharp point to a figurative one: a sharp taste that pricks the tongue. Add '-y,' and you get 'tangy' — full of that flavorful jab.