mar (n.)
mar (v.)
- blemish
 - blight
 - blot
 - blunder
 - boggle
 - botch
 - bruise
 - bumble
 - bungle
 - butcher
 - check
 - cicatrize
 - crack
 - craze
 - damage
 - deface
 - deform
 - destroy
 - disfigure
 - distort
 - flaw
 - flounder
 - fumble
 - harm
 - hurt
 - impair
 - kink
 - lumber
 - muddle
 - muff
 - murder
 - mutilate
 - offend
 - prejudice
 - ruin
 - scab
 - scar
 - scarify
 - scratch
 - slip
 - split
 - spoil
 - stain
 - stumble
 - taint
 - tarnish
 - trip
 - truncate
 - twist
 - uglify
 - vitiate
 - warp
 - wreck
 
mar (adj.)
Striving to better, oft we mar what's well.
Mend your speech a little,
Lest it may mar your fortunes.