in AM, use humorless If you accuse someone of being humourless, you mean that they are very serious about everything and do not find things amusing. adj
He was a straight-faced, humourless character.
Translation English Cobuild Collins Dictionary
dour, dry, heavy-going, intense, po-faced, serious, solemn, straight, unamused, unamusing, unfunny, unsmiling
English Collins Dictionary - English synonyms & Thesaurus
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