noun
reserve; restraint; hesitation
Almost exclusively used in the set phrases 忌憚のない (frank, unreserved) and 忌憚なく (without reserve). The standalone noun is rare.
See also: 忌憚のない
忌憚のないご意見をお聞かせください。
Please give us your frank opinion.
会議では忌憚なく話し合いましょう。
Let's discuss without reserve at the meeting.
noun, noun or participle which takes 'suru', transitive verb
Obsolete standalone noun and suru-verb meaning strong dislike or repugnance. Not used in modern Japanese; the sense is preserved only in historical or literary contexts.
古語では「忌憚する」と書いて強く嫌う意味を表した。
In classical language, 忌憚する was written to express strong dislike.