deep, large, long
small, thin
faint, visible
jagged
nasty, ugly
permanent
emotional, mental, psychological
Her mental scars will take time to heal.

acne, bullet
battle

leave
bear (often figurative)
The countryside still bears the scars of the recent hurricane.

expose, reveal
hide

remain
form
fade, heal
run
She had a long scar running down her face.

tissue

scar on
The cut left a permanent scar on his arm.

badly, deeply, heavily, hideously
His face was badly scarred by the fire.

emotionally, mentally, physically, psychologically
She was both physically and mentally scarred by the accident.

forever, permanently

with (figurative)
Their minds were scarred with bitterness.

be scarred for life, leave sb scarred
The accident left him permanently scarred.