|Definition - The contracted form of an independent word when it is used as a dependent affix, e.g. the 'm in I'm and the 'll in they'll.|
Etymology - The word derives from the Greek klinein, to lean.
Oxford English Dictionary - Its first citation is from 1946:
"Many languages have elements that
(1) combine phonologically with words with which they do not form morphological constructions, and
(2) do not constitute derivational or inflectional formatives.… The term ‘clitics’ may … be employed in this general meaning."
( E. A. Nida Morphology vii. 155)