a mixture (of sorts of one thing, different foods etc)

composite, mix

having many parts

combination, mixture

(a process of) mixing or uniting different things into one

melding; mixture

the activity of mixing or being mixed; something made by mixing; (single only) a variety (of qualities, feeling etc)

combination

(an instance of) joining or uniting and being joined; a nation formed by joining a group of countries or states

merger, joining