adjective
Definition: In a position that is above or on the highest part of something.
Example: The cat sat atop the fence, watching the birds.
adverb
Definition: In a position that is on top of something.
Example: The cat sat atop the fence, watching the birds.
preposition
Definition: In a position directly above something else; on top of.
Example: The cat sat atop the fence, watching the birds.