rodent vs gnawer

rodent and gnawer both are nouns.

Word	Noun	Adjective	Verb	Adverb
rodent	Yes	No	No	No
gnawer	Yes	No	No	No

As nouns, rodent and gnawer are synonyms defined as:

rodent and gnawer: relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing

rodent (noun)	gnawer (noun)
relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing	relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing