headly

From Middle English hedly, havedlich, from Old English hēafodlīċ (“at the top, principal, capital, deadly”), equivalent to head +‎ -ly.

headly (comparative more headly, superlative most headly)

1. (archaic) Chief; principal; capital; (of sins) deadly.
   • 1623, Shakespeare, King Henry V.:

     O'er blows the filthy and contagious clouds / Of headly murther, spoil, and villainy.

2. (archaic) Heady; violent; impetuous.

• Hadley, Haydel