Question

Why is "the rape of the lock" called a "mock epic"?

Answer 1

The epic is a narrative poem, of supposed divine inspiration, treating of a subject of great and momentous importance for mankind, the characters of the story being partly human and partly divine, and the language and style in which the incidents are related being full of elevation and dignity.

if long narrative satisfy  all the tests of epic poetry, but if the subject which is celebrated be of a trivial nature, like the cutting off a lock of a woman's hair, which is the story that is related in Pope's The Rape of the Lock, then such a poem is called a mock-epic poem