morphophoneme
Technical term in linguistics referring to a phonological unit that represents a morpheme's abstract sound form, often used in morphophonemic analysis.
A morphophoneme refers to the underlying phonological unit of a morpheme.
形態素 (morpheme) is the smallest meaningful unit, while 形態音素 (morphophoneme) is the abstract sound unit representing a morpheme's phonological form.
音素 (phoneme) is a basic sound unit that distinguishes meaning, whereas 形態音素 is a phoneme considered at the morphological level.
Compound of 形態 (form, shape) + 音素 (phoneme), likely a calque from English 'morphophoneme'.