gaffe or (rare) gaff /gaf/

A blunder

• knives
• kniving
• knob
• knobbed
• knobber
• knobbers
• knobbier
• knobbiest
• knobbiness
• knobbinesses
• knobble
• knobbled
• knobbles
• knobblier
• knobbliest
• knobbling
• knobbly
• knobby
• knobhead
• knobheads
• knobkerrie
• knobkerries
• knobs
• knobstick
• knobsticks