There exist many words whose meanings are opposites of themselves. You may ask, how can a word be an antonym of itself?
Through polysemy and homonymy, a word that is pronounced or spelled the same way can have opposite meanings. A word that is an antonym of itself is called a contronym.
Here’s the list of some contronyms:
Clip can mean “to bind together” or “to separate.” You clip sheets of paper to together or separate part of a page by clipping something out. Clip is a pair of homographs, words with different origins spelled the same.
Old English clyppan, which means “to clasp with the arms, embrace, hug,” led to our current meaning, “to hold together with a clasp.” The other clip, “to cut or snip (a part) away,” is from Old Norse klippa, which may come from the sound of a shears.
Continue usually means to persist in doing something, but as a legal term it means stop a proceeding temporarily.
3. Fight with
Fight with can be interpreted three ways. “He fought with his mother-in-law” could mean “They argued,” “They served together in the war,” or “He used the old battle-ax as a weapon.”
Meaning “to punish by caning or whipping,” flog shows up in school slang of the 17th century, but now it can have the contrary meaning, “to promote persistently,” as in “flogging a new book.” Perhaps that meaning arose from the sense ‘to urge (a horse, etc.) forward by whipping,’ which grew out of the earliest meaning.
Go means “to proceed,” but also “give out or fail,” i.e., “This car could really go until it started to go.”
6. Hold up
Hold up can mean “to support” or “to hinder”: “What a friend! When I’m struggling to get on my feet, he’s always there to hold me up.”
Out can mean “visible” or “invisible.” For example, “It’s a good thing the full moon was out when the lights went out.”
8. Out of
Out of means “outside” or “inside”: “I hardly get out of the house because I work out of my home.”
Peer is a person of equal status (as in a jury of one’s peers), but some peers are more equal than others, like the members of the peerage, the British or Irish nobility.
10. Toss out
Toss out could be either “to suggest” or “to discard”: “I decided to toss out the idea.”