a grammatical term for ichidan verbs (ru-verbs): verbs whose stem changes by one step — typically ending in -iru or -eru and conjugated by dropping -ru.
「食べる」は代表的な一段動詞だ。
'taberu' is a typical ichidan (ru-) verb.
一段動詞は語幹が変わらないため、否定形は「食べない」、ます形は「食べます」になる。
Because the stem of ichidan verbs doesn't change, the negative form of 'taberu' is 'tabenai' and the -masu form is 'tabemasu'.
日本語の動詞は一段動詞と五段動詞に分けられる。
Japanese verbs are divided into ichidan and godan verbs.