If you rush headlong into something, you do it quickly without thinking carefully about it. Do not leap headlong into decisions Headlong is also an adjective. the headlong rush to independence
with the head foremost; "the runner slid headlong into third base" in a hasty and foolhardy manner; "he fell headlong in love with his cousin" at breakneck speed; "burst headlong through the gate
If you move headlong in a particular direction, you move there very quickly. He ran headlong for the open door
with the head foremost; "a headfirst plunge down the stairs"; "a headlong dive into the pool"