What is a synonym of trivial?

Basic, petty, fundamental, minor, or inconsequential.

No. Trivia is a noun whereas trivial is the adjective. An adjective synonym would be minor, petty, unimportant.

Both are correct.

Synonym means: a word having the same or nearly the same meaning as another in the language. Definition means: the act of defining or making definite, distinct, or clear / the formal statement of the...

The word no can be replaced in some contexts by none, negative, zero, or nothing.