na-adjective, noun
careless; thoughtless; rash; rude
Describes a person or action that is careless, thoughtless, or rash, often leading to mistakes or rudeness. Somewhat literary; in everyday speech 不注意 or 軽率 is more common.
彼の粗忽な発言が会議の雰囲気を悪くした。
His careless remark spoiled the atmosphere of the meeting.
粗忽者と言われないように気をつけなさい。
Be careful not to be called a careless person.
The kanji 粗 (coarse, rough) and 忽 (neglect, disregard) combine to suggest a rough, neglectful nature. The exact historical derivation is uncertain.