Noah Webster's New International Dictionary of the English Language

1. (a. & adv.) With the head foremost; as, to fall headlong.

2. (a. & adv.) Rashly; precipitately; without deliberation.

3. (a. & adv.) Hastily; without delay or respite.

4. (a.) Rash; precipitate; as, headlong folly.

5. (a.) Steep; precipitous.