noun
boorishness; coarseness; stupidity
Dated term for a person who is uncouth, tactless, or lacking refinement; often used as a mild insult. The word combines 野暮 (rustic, boorish) with the suffix 天, which adds a derogatory or emphatic tone.
あんな野暮天とは付き合いたくない。
I don't want to associate with such a boor.
彼は野暮天だから、冗談が通じない。
He's so uncouth that jokes don't get through to him.
無粋 also means 'tactless' or 'lacking in taste', but is less colloquial and does not carry the same old-fashioned, insulting tone as 野暮天.
Compound of 野暮 (rustic, boorish) and the suffix 天, which adds a derogatory or emphatic nuance. The exact origin of 天 in this context is uncertain, but it may be related to similar derogatory suffixes in Edo-period slang.