noun, na-adjective
Refers to an avoidable mistake, oversight, or lapse in judgment, often with a sense of regret. Common in the phrase 不覚を取る (to suffer a defeat or make a blunder).
あんなミスをするとは不覚だった。
It was a blunder to make that kind of mistake.
彼は不覚の涙を流した。
He shed tears in spite of himself.
noun, na-adjective
Rare, literary use for loss of consciousness or being unaware. More commonly expressed as 意識不明 or 気絶 in modern Japanese.
その一撃で彼は不覚に陥った。
He fell unconscious from that single blow.
From Middle Chinese 不覚 (bjuw kæwk, literally 'not awake/aware'). The kanji 不 (not) and 覚 (awake, perceive) combine to mean 'unawareness' or 'failure to realize', which extended to 'blunder' in Japanese.