Words or expressions that have two contradictory meanings are known as contranyms, or contronyms, antagonyms, autoantonyms or Janus words (Janus being a Roman god who is depicted with two faces). Generally the context provides us with the intended meaning of the word ; however, these contradictions give us plenty of opportunities for word play.
A selection of contranym verbs :
To bolt: to secure /to flee
She bolted the door and then she bolted.
To buckle: to fasten/to bend and break
He buckled his belt, even though it was buckling under the strain.
To clip: to connect /to separate
She clipped the papers together and then went to the garden to clip the overgrown plants.
To dust : to remove dust/ to add dust
He dusted the kitchen while his sister dusted the cake with icing sugar.
To execute: to begin/to kill
He had executed a plan which would result in his being executed.
To hold up: to support/ to delay
The nurse had to physically hold up the patient while the doctor was held up in traffic.
To trim: to decorate/ to remove any excess
After trimming the Christmas tree, he trimmed his beard.
To wind up : to start/to finish
She wound up the old clock and decided to wind up her business.
How do contranyms come about?
These contradictory meanings can happen for various reasons. Sometimes they are literally two different words with a separate etymology, which purely by chance, are spelt in the same way. Or a contranym could owe its double meaning to polysemy, that is, when a word actually does have different meanings. The verb “to bolt” originates from a crossbow bolt (i.e. an arrow) which can both move quickly and immobilize someone. As a result, we use it for both ideas of running away speedily and securing an object, such as a door. Nouns such as dust can become verbs for either adding or removing the said noun. There are probably other reasons for contranyms due to the ongoing evolution of language – for example, the difference between British and American English. All in all, there are many strands to the complexity of the English language.