With the head first or down. / With an unrestrained forward motion. / Rashly; precipitately; without deliberation; in haste, hastily.

Precipitous. / Plunging downwards head foremost. / Rushing forward without restraint. / (figuratively) Reckless, impetuous.

(transitive) To precipitate.

(archaic) Headlong

Headlong quality or speed; precipitateness.

simple past tense and past participle of headlong

present participle of headlong

(obsolete) headlong