morphophoneme
Technical term in linguistics referring to a phonological unit that represents a morpheme's abstract sound form, often used in morphophonemic analysis.
形態音素は、形態素の基底にある音韻的な単位を指す。
A morphophoneme refers to the underlying phonological unit of a morpheme.
Compound of 形態 (form, shape) + 音素 (phoneme), likely a calque from English 'morphophoneme'.