un- + conformity → unconformity (“lack of conformity”)
(added to nouns) contrary to traditional norms; unconventional
un- + conference → unconference
prefix
(added to verbs) the inverse of a specified action
un- + dress → undress (“to take one's clothes off”)
un- + lock → unlock (“to undo the locking of”)
(added to nouns to form verbs) deprive of, release from, free from, remove from, extract from
un- + cage → uncage (“to release from a cage”)
un- + tangle → untangle (“to remove the tangling of”)
(rare) intensifying a verb that already suggests opposition or removal
un- + loosen → unloosen
un- + decipher → undecipher
un- + thaw → unthaw
prefix
(chemistry) Used for the digit one to form systematic element names of elements whose existence has been predicted, and which have not yet been given a trivial name.