combine vs synthesise

combine is a noun but synthesise is not a noun.

Word	Noun	Adjective	Verb	Adverb
combine	Yes	No	Yes	No
synthesise	No	No	Yes	No

As verbs, synthesise is a hyponym of combine; that is, synthesise is a word with a more specific, narrower meaning than combine:

Other hyponyms of combine include totalise, totalize, recombine, mix, synthesize.

combine (noun)	synthesise (noun)
harvester that heads and threshes and cleans grain while moving across the field
an occurrence that results in things being united
a consortium of independent organizations formed to limit competition by controlling the production and distribution of a product or service

combine (verb)	synthesise (verb)
mix together different elements	combine so as to form a more complex, product
put or add together
combine so as to form a whole; mix
gather in a mass, sum, or whole
add together from different sources
join for a common purpose or in a common action
have or possess in combination