the typical ending of the first element of compounds of Latin words, as -o-, is of Greek words, but often used in English with a first element of any origin, if the second element is of Latin origin:
cuneiform; Frenchify.
British Dictionary definitions for -i-
-i-
connective vowel
1.
used between elements in a compound word: cuneiform, coniferous Compare -o-
Word Origin
from Latin, stem vowel of nouns and adjectives in combination