verb

furrow one’s brows in an expression indicating disapproval, displeasure, or concentration.

he frowned as he reread the letter

scowl,glower,glare,lour,look sullen,make a face,look daggers,give someone black looks,knit/furrow one’s brows,give someone dirty looks,give someone a death stare

noun

a facial expression indicating disapproval, displeasure, or concentration, characterized by a furrowing of one’s brows.

a frown of disapproval

scowl,glower,glare,black look,dirty look,knitted brows,furrowed brows,death stare