cellular phone vs cellphone

cellular phone and cellphone both are nouns.

Word	Noun	Adjective	Verb	Adverb
cellular phone	Yes	No	No	No
cellphone	Yes	No	No	No

As nouns, cellular phone and cellphone are synonyms defined as:

cellular phone and cellphone: a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver

Other synonyms of cellular phone include cell, cellular telephone, mobile phone.

cellular phone (noun)	cellphone (noun)
a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver	a hand-held mobile radiotelephone for use in an area divided into small sections, each with its own short-range transmitter/receiver