excessively quick; "made a hasty exit"; "a headlong rush to sell"
with the head foremost; "a headfirst plunge down the stairs"; "a headlong dive into the pool"
with the head foremost; "the runner slid headlong into third base"
at breakneck speed; "burst headlong through the gate"
in a hasty and foolhardy manner; "he fell headlong in love with his cousin"