gaffe or (rare) gaff /gaf/

A blunder

• hard cases
• hard cash
• hard cheese
• hard coal
• hard copies
• hard copy
• hard-copy
• hard core
• hard-core
• hard court
• hard courts
• hardcover
• hard-cured
• hard currencies
• hard currency
• hard disk
• hard disk drive
• hard disk drives
• hard disks
• hard done by
• hard-drawn
• hard drinker
• hard drinkers
• hard drive
• hard drives