Plural of 'couth' when used as a noun; or third-person singular verb form (he/she couths).
Formed from 'couth' by regular English pluralization (-s) or verb conjugation, creating forms that are theoretically possible but rarely used in practice.
The fact that 'couths' could be a verb meaning 'acts with couth' shows how readily English treats words—even invented back-formations can become verbs if you need them.
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