1. (informal) to act or begin too soon or without due caution 
2. To begin a race too soon, before the starting gun goes off

Derived forms: jumped the gun

• Hayastan
• haycock
• Haydn
• Hayek
• Hayes
• hayfield
• hayfork
• haying
• haying time
• hayloft
• Haym Salomon
• haymaker
• haymaking
• haymow
• hayrack
• hayrick
• hayride
• hayrig
• Hays
• hayseed
• haystack
• Hayti
• hayward
• haywire
• Haywood