segment vs metamere

segment and metamere both are nouns.

Word	Noun	Adjective	Verb	Adverb
segment	Yes	No	Yes	No
metamere	Yes	No	No	No

As nouns, metamere is a hyponym of segment; that is, metamere is a word with a more specific, narrower meaning than segment:

segment: one of the parts into which something naturally divides
metamere: one of a series of similar body segments into which some animals are divided longitudinally

Other hyponyms of segment include somite, sarcomere, section, internode.

segment (noun)	metamere (noun)
one of several parts or pieces that fit with others to constitute a whole object	one of a series of similar body segments into which some animals are divided longitudinally
one of the parts into which something naturally divides

segment (verb)	metamere (verb)
divide into segments
divide or split up