What is the meaning of Imide?

A compound with, or derivative of, the imido group; specif., a compound of one or more acid radicals with the imido group, or with a monamine; hence, also, a derivative of ammonia, in which two atoms of hydrogen have been replaced by divalent basic or acid radicals; -- frequently used as a combining form; as, succinimide.

Source: Webster’s Revised Unabridged Dictionary (1913), via OPTED