1. [ [Undefined_variable] ] determiner, none of the two
2. [ adverb ] after a negative statement used to indicate that the next statement is similarly negative

"I was not happy and neither were they" "just as you would not complain, neither should he"

3. [ conjunction ] conjunction, not one and not the other
Synonyms: nor
4. [ [Undefined_variable] ] pronoun, none of a set of persons
Synonyms: no_one nobody no none no-one
Similar spelling:   nether