The likely primitive form of the Classical Adûnaic plural inflection -î- (SD/429), appearing in a few examples of primitive plurals in the form -yi: manaw+yi, izray+yi (SD/424). Tolkien gave no indication of whether the primitive inflection was also used as an infix, as was the case for Classical Adûnaic plurals of strong-nouns.
Adûnaic
-î-
suffix. plural inflection
The inflection used to mark nouns as plural (S/429), used either as a suffix (for weak-nouns) or replacing the last vowel (for strong-nouns). According to Tolkien, the primitive form of this suffix was most likely ✶-yī (SD/424). See the entry on the plural nouns case for further details.