Definition - A letter, syllable, or word affixed to the end of a word to form a new word.

Example -
The -ly in quickly and the -s in dogs.

Etymology -
Based on the model of prefix, the word was coined by combining post and fix.

Oxford English Dictionary -
Its first citation is from 1805:
"Diminutive postfixes were added to the names of streams, &c. — Sruth is Gaelic for stream; Sruthan is little stream."
(G. Dyer Restor. Anc. Modes bestowing Names 43)

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