Is 出くわす a 他動詞 that's intransitive?


According to [a video on transitive/intransitive
verbs](https://youtu.be/ELk1dqaEmyk), "Cure Dolly" states that whether a verb
ends in す is "always" a reliable indicator on whether it is an "other-move"
verb (他動詞):

> [![enter image description
> here](https://i.stack.imgur.com/qTgeI.png)](https://i.stack.imgur.com/qTgeI.png)

Yet according to [my
dictionary](https://jpdb.io/search?q=%E5%87%BA%E3%81%8F%E3%82%8F%E3%81%99&lang=english#a),
the verb 出くわす is _intransitive_ :

> [![enter image description
> here](https://i.stack.imgur.com/qZYSO.png)](https://i.stack.imgur.com/qZYSO.png)

**Question:** Is this one of those rare situations where transitivity and
"other-moveness" (他動詞) diverges, so that 出くわす is an 他動詞 but still
intransitive? Or is Cure Dolly's rule just wrong?




That rule is mostly true, especially for simple verbs, but it's not always
true. There are a few exceptional cases where what was originally a transitive
verb is now interpreted as an intransitive verb.

One example is [暮らす](https://jisho.org/word/%E6%9A%AE%E3%82%89%E3%81%99),
which is normally regarded as an intransitive verb today. According to 明鏡国語辞典,
it was originally a transitive (or causative) version of
[暮れる](https://jisho.org/word/%E6%9A%AE%E3%82%8C%E3%82%8B), but something like
"to make days end" eventually became an independent intransitive verb meaning
"to live (a life)".

When it comes to compound verbs, there are quite a few intransitive verbs that
end with す, including 踊り明かす, 泣きはらす, 鉢合わす and 怒り散らす.

As for 出くわす, I could not find any authoritative source regarding its
etymology. But it may be related to 交はす【くわす】, which is a transitive verb
meaning "to cross/exchange (something)" in classical Japanese (its modern
equivalent is 交わす【かわす】). This may be another example of a verb that changed
its transitivity while being used as a compound verb. Cure Dolly's rule is
useful when you learn words, but this is not a rule recognized by an average
Japanese person, and there is seldom a 100% correct rule in the world of
vocabulary, anyway.




That rule is mostly true, especially for simple verbs, but it's not always
true. There are a few exceptional cases where what was originally a transitive
verb is now interpreted as an intransitive verb.

One example is [暮らす](https://jisho.org/word/%E6%9A%AE%E3%82%89%E3%81%99),
which is normally regarded as an intransitive verb today. According to 明鏡国語辞典,
it was originally a transitive (or causative) version of
[暮れる](https://jisho.org/word/%E6%9A%AE%E3%82%8C%E3%82%8B), but something like
"to make days end" eventually became an independent intransitive verb meaning
"to live (a life)".

When it comes to compound verbs, there are quite a few intransitive verbs that
end with す, including 踊り明かす, 泣きはらす, 鉢合わす and 怒り散らす.

As for 出くわす, I could not find any authoritative source regarding its
etymology. But it may be related to 交はす【くわす】, which is a transitive verb
meaning "to cross/exchange (something)" in classical Japanese (its modern
equivalent is 交わす【かわす】). This may be another example of a verb that changed
its transitivity while being used as a compound verb. Cure Dolly's rule is
useful when you learn words, but this is not a rule recognized by an average
Japanese person, and there is seldom a 100% correct rule in the world of
vocabulary, anyway.

