I'm wondering about the origin of the word 無くす.

There is the word 無{な}い, meaning "to not exist/be there". You can add なる and する to adjectives to create verbs:

  • なる - 無くなる - "to become not there/become lost"
  • する - 無くする - "to make not there/lose"

Now, according to some dictionaries, 無くなる seems to be considered a word of its own, but not 無くする, which I find interesting.

無くす means the same thing as 無くする, and the definition in デジタル大辞泉 of 無くす does use 無くする.

Thus, I am wondering if 無くす stems from 無くする, but with the る dropped, in the same way as 愛す appeared.

  • What Dim said also applies for 愛す and other noun+す verbs. す is not する with the -る dropped; on the contrary, する is す with a -る tacked on (actually する is a particular inflection of す which became generalized). In sentence-final position, す is the old form and する the newer. Commented Jun 26, 2017 at 17:38

1 Answer 1


す is the 文語体【ぶんごたい】 (old form) of する. する was originally the 連体形【れんたいけい】 (adnominal form) of す. It was combined with the 終止形【しゅうしけい】 (dictionary form) later.

Though 無【な】くす stems from 無【な】く + す, it is not considered to be a word created by adding す, but is instead thought of as a word like 荒【あ】らす, 殺【ころ】す, etc. (Usually the す in words created by adding す is low pitch, such as 愛す, read as あいす【HLL】, but the one in 無くす is read as なくす【LHH】 with a high pitch.) For this reason, 無くする is uncommon. Most dictionaries in Japan don't give 無くする as an entry.

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