A man jumps headfirst into the sea.
- An example of headfirst is taking on a difficult project without giving it any thought.
- An example of headfirst is sledding down a hill, belly down and face first.
Headfirst is defined as doing without much thought, or leading with the head.
- with the head in front; headlong
- in a reckless way; rashly; impetuously
with or done with the head first or foremost; headlong
- With the head leading; headlong: went headfirst down the stairs.
- Impetuously; brashly.