Stupid is a related term of irksome.
As adjectives the difference between stupid and irksome
is that
stupid is lacking in intelligence or exhibiting the quality of having been done by someone lacking in intelligence while
irksome is disagreeable or troublesome by reason of long continuance or repetition; bothersome; annoying; irritating; wearisome; tedious.
As an adverb stupid
is (slang|dated) extremely.
As a noun stupid
is a stupid person; a fool.