fear vs frighten

fear is a noun but frighten is not a noun.

Word	Noun	Adjective	Verb	Adverb
fear	Yes	No	Yes	No
frighten	No	No	Yes	No

fear (noun)	frighten (noun)
an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)
an anxious feeling
a feeling of profound respect for someone or something

fear (verb)	frighten (verb)
be afraid or scared of; be frightened of	cause fear in
regard with feelings of respect and reverence; consider hallowed or exalted or be in awe of
be sorry; used to introduce an unpleasant statement
be afraid or feel anxious or apprehensive about a possible or probable situation or event
be uneasy or apprehensive about