What Is the Stem Form?
Just as the English verb "see" can become "sees," "saw," or "seen," Japanese verbs do the same. While these different verb forms indicate only the number of subjects, types of subjects, and tenses in English, in Japanese they are utilized to show a wider range of meanings. For example, 見る (to see) can change form to 見た (saw), 見ている (to be seeing), 見ていて (see, and), 見よう (let's see), 見たら (if saw…), and the list goes on. This variation of the verb form is called "conjugation."
The "conjugation" doesn't transform the whole verb into an entirely new verb (aside from a couple of irregular exceptions). Japanese verbs consist of the fixed part and the part that can conjugate, and only the verb suffixes can change form. The fixed part is called the stem form, and we refer to this fixed part (plus the vowel い for godan verbs) as stem form.
The name actually varies, so depending on your teacher or textbook, you may also see stem form listed as V-stem, verb stem, ます form, masu form, i-form, 連用形, ren'you-kei, continuative form, continuative stem, conjunctive form, or sentence-joining form.
Learning how to make the stem form is very useful because it is used in many different types of verb conjugations. Furthermore, it can also stand alone as a noun at times or become at least noun-like, allowing it to combine with another word to form a compound verb like 飛び込む (to jump in).
Thus, in this post, we'll focus on how to change Japanese verbs, which end in る or う (vowel u), to the stem form.
|Godan||会う → 会い
立つ → 立ち
写す → 写し
代わる → 代わり
書く → 書き
泳ぐ → 泳ぎ
死ぬ → 死に
学ぶ → 学び
休む → 休み
|Ichidan||食べる → 食べ
起きる → 起き
閉じる → 閉じ
|Irregular|| 来る → 来
する → し
For godan verbs, simply replace the う-ending kana to the い-ending kana to make the stem form. Now let's try making the stem form of the verb 買う (to buy). 買う (kau) becomes 買い (kai). Period. This one was easy because 買う ends in the vowel う as is.
Let's try another example: how about 読む (to read)? Change 読む (yomu) into 読み (yomi). Just like that, 書く (to write) becomes 書き (kaki), 話す (to speak) becomes 話し (hanashi), and 遊ぶ (to play) becomes 遊び (asobi).
For ichidan verbs, simply remove the last る, and that's it. No need to add anything. Easy! So the stem form of 見る (to look) is 見, 起きる (to wake up) is 起き, 落ちる (to fall) is 落ち, 開ける (to open) is 開け, 見せる (to show) is 見せ, 寝る (to sleep) is 寝, and 食べる (to eat) is 食べ.