Open English Wordnet
Adjectives
(s)head-oncharacterized by direct opposition“a head-on confrontation” (s)frontal, head-onmeeting front to front“a frontal attack”,
“a head-on collision” Adverbs
(r)head-onin direct opposition; directly“we must meet the problem head-on” (r)head-onwith the front foremost“the cars collided head-on”