noun which may take the genitive case particle 'no', noun
thoughtless; inconsiderate; unthinking
Describes a person or action lacking careful thought or consideration for others. Often used as a noun or with な/の to modify nouns.
彼の考えなしな発言がみんなを傷つけた。
His thoughtless remark hurt everyone.
考えなしに行動すると失敗するよ。
If you act without thinking, you'll fail.
More formal and literary; emphasizes lack of prudence or deliberation.
Focuses on rashness or carelessness, often implying a hasty decision.
Compound of 考え (thought) + なし (without). The exact historical derivation is straightforward; the word is a transparent combination of its parts.