五段活用

Etymology
Compound of 🇰🇲.

Literally, refers to how the inflected endings are located in the gojūon table. It means five vowels are involved, since each of the table contains one vowel. Thus, this can be understood as "five-voweled conjugation".

Noun

 * 1)  a verbal conjugation class consisting of five alternating bases: -a, -i, -u, -e, and -o