Except

Except[c] is a pattern object that matches any expression except one that matches c.

Except[c, p] matches any expression that matches p but not c.

Examples

Match anything except a specific value:

Cases[{1, 2, 3, a, b}, Except[2]]
(* {1, 3, a, b} *)

Match integers except specific ones:

Cases[{1, 2, 3, 4, 5}, Except[2 | 4, _Integer]]
(* {1, 3, 5} *)

Please visit the official Wolfram Language Reference for more details.