headfirst

/HH EH1 D F ER1 S T/
adjective
  1. 1

    With the head in front; headlong.

adverb
  1. 1

    With the head in front; headlong.

  2. 2

    Rashly; precipitately; without deliberation; hastily.

Source: https://en.wiktionary.org/wiki/headfirst