Definition -
(1) The phonetic realization of a morpheme.
(2) A phoneme or series of phonemes forming a variant or a number of variants of a morpheme. (OED)

Etymology -
The term was coined by contracting the French morphème.

Oxford English Dictionary -
Its first citation is from 1947:
"Recurrent partials not composed of smaller ones (-way) are alternants or morphs.…"
(C. F. Hockett in Language XXIII. 322)

Quotation -
The relationship between a morpheme and its morphs and allomorphs is parallel to the relationship between a phoneme and its phones and allophones. A morpheme is manifested as one or more morphs (surface forms) in different environments. These morphs are called allomorphs. A phoneme is manifested as one or more phones (phonetic sounds) in different environments. These phones are called allophones.

Please comment