humourless

/HH Y UW1 M ER0 L AH0 S/
adjective
  1. 1

    Lacking humor or levity; serious; not funny, amusing, amused, or lighthearted.

    โ€œHe watched the little dog's antics with a humorless stare.โ€

Source: https://en.wiktionary.org/wiki/humorless, https://en.wiktionary.org/wiki/humourless