One who denies (in various senses of the verb).

= denier, n.1

as n. An incredulous person.

In general sense: One who does not believe in something specified; an unbeliever. Const. in, †to, †against. (Frequently figurative from sense A. 3).

One who disbelieves or refuses belief; an unbeliever.

A person who denies the existence of something; a person who rejects a doctrine, belief, etc. Cf. explode, v. 1a. Obsolete.

as n. An inconvincible person.