bound morpheme
Definition - A morpheme that cannot stand alone as a word.
Note: A morpheme that CAN stand alone as a word is called a free morpheme.

Example -
The word undone has two morphemes:
(1) the bound morpheme un- and
(2) the free morpheme done.

Oxford English Dictionary -
The concept's first citation is from 1948:
"If it is a bound form, the element must — in order to be a morpheme — be active."
(Word Apr. 20)

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