Definition - In linguistics, the atomic unit of meaning (i.e. the smallest meaningful unit).

1. A morpheme is free if it can stand alone, and it is bound if it can't. For example, the word undone has two morphemes: the bound morpheme un and the free morpheme done.

Example -
The ing in coming is a morpheme, but the g is not.

Etymology -
The word derives from the French morphème, which was coined from the Greek morphe, form or shape.
Note: It was based on an analogy with the previously existing word phonème.

Oxford English Dictionary -
Its first citation is from 1896:
"The phonetic elements of a given word are its phonemes. But its significant elements, be they root, suffix, prefix, inflection or aught else, are morphemes."
(R. J. Lloyd in Neueren Sprachen III. 615 )

Please comment