When it comes to words, what's a contronym?

Answer 1

A word that has two opposite meanings-such as weather, which can mean either to withstand or to erode; or buckle, which can mean to fasten or to fall apart.

Answer 2

here's dictionary.com's definition:

Main Entry: contranym
Part of Speech: noun
Definition: any word that can be its own antonym, e.g. cleave, overlook; also called antilogy, autoantonym, contronym, enantiodrome, Janus word
Example: Handicap is a good example of a contranym.
Webster's New Millennium™ Dictionary of English, Preview Edition (v 0.9.6)
Copyright © 2003-2005 Lexico Publishing Group, LLC

hope you understand :)