Literal in programming, is a notation for specifying a constant value.
Literal in logical expressions, e.g., DNFs is a variable or a negated variable.
Literal in regular expressions and in descriptions of formal grammars is a synonym of terminal symbol (which is used in the formal language "literally", rather than generates a chain of substitutions).
Literal in data compression is a chunk of input data that are represented "as is" in the compressed data.