Question about conjugating verb + たい


Why is 帰る conjugated 帰りたい and not 帰たい when adding たい to it?

Is it conjugated this way because 帰る is a godan verb?




As surmised in your question, and confirmed by user3856370 in the comment,
帰【かえ】る ("to return", intransitive") is a 五段【ごだん】 verb, and this is why たい
needs that り before it.

### The grammar

More specifically, the ～たい desiderative ("want to") ending attaches to the
連用形【れんようけい】, the continuative or stem form of the verb. This is sometimes
called the " _-masu_ stem" in English, since it's the form of the core verb
that gets the _-masu_ on the end.

### Mechanics for 五段【ごだん】 or "type I" verbs

For instance, 行【い】く ("to go") in the plain or dictionary form becomes 行【い】きます
in the polite or _-masu_ form. The verb stem here, the 連用形【れんようけい】 for this
verb, is 行【い】き. So to conjugate into the desiderative, we would take that stem
行【い】き and stick the ～たい auxiliary or suffix onto the end, giving us 行【い】きたい.

### Mechanics for 一段【いちだん】 or "type II" verbs

For the 一段【いちだん】 verbs, the verb stem is the same for all of the different
conjugations -- that's actually what 一段【いちだん】 means here, there's just the one
段【だん】 ("grade, step") -- that is, there's just the one vowel on the end,
either _-e_ or _-i_ depending on the verb. So for 変【か】える ("to change",
transitive), the plain form 変【か】える becomes _-masu_ form 変【か】えます, so we know
the _-masu_ stem or 連用形【れんようけい】 is 変【か】え. To conjugate into the desiderative,
we take that stem 変【か】え and stick the ～たい auxiliary or suffix onto the end,
giving us 変【か】えたい.

### Note about homophones

Some verbs, like 帰【かえ】る and 変【か】える, sound almost the same. (The pitch accent
is different, but in terms of kana spellings, they are identical.) In these
cases, you basically just have to learn which is which and remember the
conjugation rules. Thankfully there aren't that many verbs like this. :)

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Please comment if the above does not answer your question.

