noun
/ˈsɪnɵəsəs/ , pl -theses /-ɵəˌsiːz/
[count] formal :something that is made by combining different things (such as ideas, styles, etc.) - often + of
technical :the production of a substance by combining simpler substances through a chemical process [count]
usually singular; often + of
[noncount] :the production of sounds or speech by using electronic equipment