mandible vs lower jawbone

mandible and lower jawbone both are nouns.

Word	Noun	Adjective	Verb	Adverb
mandible	Yes	No	No	No
lower jawbone	Yes	No	No	No

As nouns, mandible and lower jawbone are synonyms defined as:

mandible and lower jawbone: the jaw in vertebrates that is hinged to open the mouth

Other synonyms of mandible include jawbone, jowl, lower jaw, mandibula, mandibular bone, submaxilla.

mandible (noun)	lower jawbone (noun)
the jaw in vertebrates that is hinged to open the mouth	the jaw in vertebrates that is hinged to open the mouth