Can A Word Be Its Own Opposite?

Yes! They are called Contronyms - words that are their own antonyms, depending on usage.

To all who love the English language, here are a few examples

DUST:  can mean ‘to add fine particles’ or ‘to remove fine particles’.

LEFT:  can mean both  ‘remaining’ and ‘departed’.

OFF:  can mean both ‘activated’ and ‘deactivated’.

Eg:- “Set off” - Activated

“ Switch off - Deactivated

OVERSIGHT:  means both ‘watchful care’ and ‘an inadvertent error’.

SCREEN:  can mean both ‘to show’ and ‘to hide’.

SANCTION:  can mean both ‘a penalty for disobeying a law’ and ‘official permission or approval for an action.