let (someone) off

to not punish someone.

The judge let the boys off because they hadn't ever been in trouble before.

Related vocabulary: off the hook

• a figment of your imagination
• a figure of fun
• a fine kettle of fish
• a fine line
• a finger in every pie
• a firm hand on the tiller
• a fishing expedition
• a fish out of water
• a flash in the pan
• a flight of fancy
• a flight of fantasy
• a flight of imagination
• a flip-flop
• a fly in the ointment
• a fly on the wall
• a fool and his money are soon parted.
• a fool's errand
• a force to be reckoned with
• a foregone conclusion
• a four-letter word
• a frame of mind
• a Frankenstein's monster
• a free agent
• a free-for-all
• a free ride