Contronyms are words that have contradictory or opposite meanings. It’s like one word that means both stop and go or hot and cold. That can be really confusing but you can usually guess the meaning from the context.
I buckled my belt. (Put the two parts together.)
The bridge buckled during the earthquake. (It came apart.)
So buckle means both, to put together and to come apart.
Contronym seems to be the most commonly used term but these words go by a lot of names. Looking around I found them called, janus words, contronyms, contranyms, autantonyms, auto-antonyms, and contradictanyms. I love the name “Janus words.” Janus was a Roman god with two faces. He was the god of transitions, doorways and times of great change like the new year. The month of January is even named after him.
|ˈkäntrəˌnim| (also contranym) nouna word with two opposite meanings, e.g., sanction (which can mean both ‘a penalty for disobeying a law’ and ‘official permission or approval for an action’).
(Source – New Oxford American Dictionary)
For more information and a list of lots of these words check out this wikipedia post.
Some of my favorites are:
Garnish: To furnish, as with food preparation, or to take away, as with wages
Give out: To provide, or to stop because of a lack of supply
Go: To proceed or succeed, or to weaken or fail
Grade: A degree of slope, or a horizontal line or position
Strike: To hit, or to miss in an attempt to hit
Table: To propose (in British English), or to set aside
Throw out: To dispose of, or to present for consideration
Transparent: Invisible, or obvious
Trim: To decorate, or to remove excess from
Trip: A journey, or a stumble
Variety: A particular type, or many types
Wear: To endure, or to deteriorate
Weather: To withstand, or to wear away
With: Alongside, or against