Is the word each a pronoun or adjective?

The Word 'each' is both a pronoun and and adjective, and also an adverb.

The Word 'each' is a pronoun when it stands alone taking the place of a Word for one of two or more people or things.

Example: Each has been assigned a topic.

The Word 'each' is an adjective when placed before a noun to describe that noun.

Example: Each student has been assigned a topic.

The Word 'each' is an adverb when used to modify a verb as to, for, or by every one of a group.

Example: The students each have an assigned topic.