synthesiser vs synthesise

synthesiser is a noun but synthesise is not a noun.

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

synthesiser (noun)	synthesise (noun)
(music) an electronic instrument (usually played with a keyboard) that generates and modifies sounds electronically and can imitate a variety of other musical instruments
an intellectual who synthesizes or uses synthetic methods

synthesiser (verb)	synthesise (verb)
	combine so as to form a more complex, product