synthesis vs synthetical

synthesis is a noun but synthetical is not a noun.

Word	Noun	Adjective	Verb	Adverb
synthesis	Yes	No	No	No
synthetical	No	Yes	No	No

synthesis (noun)	synthetical (noun)
the combination of ideas into a complex whole
reasoning from the general to the particular (or from cause to effect)
the process of producing a chemical compound (usually by the union of simpler chemical compounds)

synthesis (adjective)	synthetical (adjective)
	involving or of the nature of synthesis (combining separate elements to form a coherent whole) as opposed to analysis
	of a proposition whose truth value is determined by observation or facts