interjection (n.)

A term used in the TRADITIONAL CLASSIFICATION of PARTS OF SPEECH, referring to a CLASS of WORDS which are UNPRODUCTIVE, do not enter into SYNTACTIC relationships with other classes, and whose FUNCTION is purely EMOTIVE, e.g. Yuk!, Strewth!, Blast!, Tut tut! There is an unclear boundary between these ITEMS and other types of EXCLAMATION, where some REFERENTIAL MEANING may be involved, and where there may be more than one word, e.g. Excellent!, Lucky devil!, Cheers!, Well well! Several alternative ways of analyzing these items have been suggested, using such notions as MINOR SENTENCE, FORMULAIC LANGUAGE, etc.