/i nish"euh liz'euhm/ , n.
1. a name or term formed from the initial letters of a group of words and pronounced as a separate word, as NATO for North Atlantic Treaty Organization; an acronym.
2. a set of initials representing a name, organization, or the like, with each letter pronounced separately, as FBI for Federal Bureau of Investigation.
3. the practice of using initials or forming words from initials.
[ 1895-1900; INITIAL + -ISM ]