expression, noun-modifying (irregular)
Idiomatic expression meaning to speak one's mind without mincing words. Often used in the form 歯に衣を着せない or 歯に衣を着せずに.
See also: 歯に衣着せぬ
He is known for his outspoken manner of speaking.
歯に衣を着せずに言うと、その計画は失敗だ。
To be frank, that plan is a failure.
Means 'without reserve' or 'frankly', but is an adverb rather than a prenominal expression.
Literally 'not putting clothes on one's teeth', an idiom meaning to speak without covering up one's words. The exact origin is uncertain, but it metaphorically suggests not dressing up one's speech.