na-adjective, noun
thoughtless; indiscreet; lacking common sense
Describes a person, action, or remark that shows poor judgment, lack of discretion, or a failure to consider the situation properly. Often used in formal or critical contexts.
彼の不見識な発言が会議の雰囲気を悪くした。
His indiscreet remark spoiled the atmosphere of the meeting.
そんな不見識な行動
Such thoughtless behavior is unacceptable.
無分別 also means thoughtless or imprudent, but 不見識 carries a stronger nuance of betraying one's ignorance or poor taste, and is more formal.
Compound of 不 (not) + 見識 (discernment, judgment). The word 見識 itself refers to insight or good judgment, so 不見識 literally means 'without discernment'.