A part of the series on English grammar and vocabulary...
Can A Word Be Its Own Opposite?
Yes! There are actually dozens of examples. They are called Contronyms—words that are their own antonyms, depending on usage.
Here are a few for starters:
Dust :
can mean
‘to add fine particles’ or ‘to remove fine particles’.
Left :
can mean both
‘remaining’ and ‘departed’.
Off :
can mean both ‘activated’ (as in set off) and ‘deactivated’.
Oversight :
means both
‘watchful care’ and ‘an inadvertent error’.
Screen :
can mean both
‘to show’ and ‘to hide’.