head off vs forbid

head off and forbid both are verbs.

Word	Noun	Adjective	Verb	Adverb
head off	No	No	Yes	No
forbid	No	No	Yes	No

As verbs, forbid is a hypernym of head off; that is, forbid is a word with a broader meaning than head off:

head off: prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off
forbid: keep from happening or arising; make impossible

Other hypernyms of head off include foreclose, forestall, preclude, prevent.

head off (verb)	forbid (verb)
prevent the occurrence of; prevent from happening; to protect from or to keep away anything undesirable; to ward off	command against
	keep from happening or arising; make impossible