They both contain vowels and consonants. So why should 1 be called consonant
and the other vowel?
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2015-05-17T23:43:28.140
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question
verbs terminology
Why are the verb groups in Japanese called "consonant-stem" and "vowel-stem"?
You'll understand if you just look at them romanized:

  1. ## Vowel-stem verbs (一段動詞)
```     　食べない　tab **e** -nai

    　食べます　tab **e** -masu
    　食べる　　tab **e** -ru  
    　食べれば　tab **e** -reba
    　食べよう　tab **e** -yoo
    
```

The stem is _tabe-_ , which ends with /e/, a vowel.

  2. ## Consonant-stem verbs (五段動詞)
```     　泳がない　oyo **g** -anai

    　泳ぎます　oyo **g** -imasu
    　泳ぐ　　　oyo **g** -u
    　泳げば　　oyo **g** -eba
    　泳ごう　　oyo **g** -oo
    
```

The stem is _oyog-_ , which ends with /g/, a consonant.

Simple as that.
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2015-05-18T00:13:57.070
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answer
When learning Japanese as a foreign language, "consonant-stem" (respectively
"vowel-stem") verbs are called thus, because **their stem _ends_ in a
consonant** (resp. **vowel** ), where "stem" refers to the part not changing
during inflection (conjugation).

> m **i** -ru, m **i** -tai, m **i** -masu, m **i** -nai, m **i** -r-eba, m
> **i** -y-ou...
>
> ki **k** -u, ki **k** -i-tai, ki **k** -i-masu, ki **k** -a-nai, ki **k**
> -eba, ki **k** -ou...

Depending on the inflection, consonant-stem verbs change the vowel coming
after the consonant in the stem. In fact, all five vowels appear, which is why
in traditional Japanese grammar (where the concepts "consonant" and "vowel"
aren't used) they are said to follow 五段活用 "five rank conjugation". The vowel
in the vowel-stem verbs doesn't change, so they follow 一段活用 "single rank
conjugation".

Note that the dichotomy consonant-stem–vowel-stem is a simplification of
traditional Japanese grammar, which further divides the ("vowel-stem") "single
rank conjugation" into "upper" and "lower" (and also ignores the verbs _suru_
and _kuru_ ). (Have a look at the table on
[Wikipedia](http://ja.wikipedia.org/wiki/Template:%E6%B4%BB%E7%94%A8%E3%81%AE%E7%A8%AE%E9%A1%9E).)
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2015-05-18T00:14:24.460
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answer