Synonyms of 'humourless'
seriousDictionary, intense, solemnHe was a straight-faced, humourless character.
Copyright © 2016 by HarperCollins Publishers. All rights reserved.
Intense is used to describe something that is very great or extreme in strength or degree.
He was sweating from the intense heat.
If you describe someone as po-faced, you think that they are being unnecessarily serious about something.
a politically-correct bastion of po-faced self-righteousness
Thesaurus for humourless from the Collins English Thesaurus
If you accuse someone of being humourless , you mean that they are very serious about everything and do not find things amusing .