deep, heavy
faint, little, slight, small, tiny
confused, puzzled, thoughtful, worried
disapproving
angry, fierce

give
The boy gave a small frown.

wear
She wore a worried frown.

crease into, form
Her face creased into a frown.

be drawn together in, draw together in
His brows drew together in a frown.

appear, disappear
darken, deepen
grow darker, grow deeper
Her frown grew deeper at the memory.

crease sth
A frown of concern creased her forehead.

mar sth
A frown marred his handsome features.

cross sth
A frown crossed her brow.

turn into sth

line

with a frown
frown of
a frown of concentration/concern

a frown on your face

darkly, deeply, heavily
slightly
disapprovingly
impatiently
thoughtfully
She studied the letter, frowning thoughtfully.

at
She turned and frowned at him.

in
He looked at the coded message, frowning in concentration.

with
He frowned with annoyance.