1. With the head foremost
   "the runner slid headlong into third base"
   - headfirst 
2. At breakneck speed
   "burst headlong through the gate"
   - precipitately 
3. In a hasty and foolhardy manner
   "he fell headlong in love with his cousin"
   - rashly

1. Excessively quick
   "a headlong rush to sell"
   - hasty, gadarene, Gadarene 
2. With the head foremost
   "a headlong dive into the pool"
   - headfirst

See also: forward, hurried

Encyclopedia: Headlong

• right of entry
• right of first publication
• right of offset
• right of privacy
• right of re-entry
• right of search
• right of way
• right on
• right on the money
• right smart
• right stage
• right to an attorney
• right to confront accusors
• right to due process
• right to liberty
• right to life
• right to privacy
• right to speedy and public trial by jury
• right to the pursuit of happiness
• right to vote
• right triangle
• right ventricle
• right whale
• right-angled
• right-angled triangle