I. -ˈlȯŋ adverb
Etymology: Middle English hedlong, alteration of hedling, from hed head
Date: 14th century
1. : headfirst 1
2. : without deliberation : recklessly
rushes headlong into danger
3. : without pause or delay
II. -ˌlȯŋ adjective
Date: circa 1550
1. archaic : steep , precipitous
2. : lacking in calmness or restraint : precipitate
a headlong torrent of emotion
3. : plunging headfirst
Synonyms: see precipitate