Bad

Something bad is a thing that has characteristics failing to match its values, often detracting therefrom.

Note that badness differs in some ways from other traits. For example, something red or hungry or fast has characteristics described with reference to some material set of properties, such as quantum light interactivity or lack of usable food energy. However, "bad" indirectly refers to a material set of properties, through a (sometimes implicit) valuation. For example, a bad depends on the reader, a bad meal depends on the eater, and so on. (Another word that refers indirectly is "this," which depends on the word user. For example, "this sentence" means the one you are reading now, but the exact same phrase would mean a different sentence if it were used elsewhere.)

The opposite of bad is good.