godan verb; consonant-stem verb; u-verb
A verb class whose stem ends in a consonant and which inflects across all five vowel rows (a, i, u, e, o). In traditional Japanese grammar, these are called 五段動詞 (godan dōshi). In linguistics, they are often referred to as consonant-stem verbs. In learner materials, they are sometimes called u-verbs or type 1 verbs.
See also: 一段動詞
"Kaku" (to write) is a godan verb.
Memorizing the conjugations of godan verbs is tough.
一段動詞 (ichidan verbs) are vowel-stem verbs that conjugate only with a single vowel row (i or e), unlike 五段動詞 which use all five rows.
From 五 (go, 'five') + 段 (dan, 'step, row') + 動詞 (dōshi, 'verb'), referring to the five vowel rows used in conjugation.