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Janus Words: Duality and contradiction

The English language is full of intriguing phenomena that can be very interesting to study, but can also be very frustrating for English learners and translators. One such phenomenon is Janus words.

Janus is the name of the Roman god of beginnings and endings, duality. He is usually depicted as having two faces, since he looks to the future and to the past. 

Janus words are, in a way, ‘two-faced’ words — words that contradict themselves, by having two opposite meanings at the same time. Janus words can also be called contronyms, antagonyms, or auto-antonyms.

Here are some examples:

  • Fast – firmly fixed or moving rapidly
  • Cleave – to divide by a cut or to join together
  • To dust – to make free of dust or to sprinkle with fine particles
  • Overlook – to look at something or to miss something, look past it
  • To scan – to look carefully or to glance quickly at

Where do Janus words come from?

Janus words can evolve in different ways. Sometimes this is a case of homographs: words that are not the same, have different origins, but over the course of history develop the same form. 


Cleave is an example of this: cleave (verb) is descended from Middle English cleven, from Old English cleofan; meaning to split. On the other hand, cleave as an intransitive verb is descended from Middle English clevien, from Old English clifian, meaning to stick. Thus you have two different sources for, what today looks like a single word that is its own antonym.

Many Janus words develop their contradictory meanings through semantic broadening when a word with a specific meaning develops a wider, more general semantic meaning. 


Peruse used to mean to ‘examine something item by item’. Then it gained a more general meaning of ‘examining something carefully’. Later, this developed into an opposite meaning of ‘looking at something in a relaxed way’.

The opposite can also happen: a word with a broad meaning can develop more specific meanings that end up being contradictory to each other.


Sanction is an example of such a word. When it appeared in the English language, it referred to an oath. Over time, it came to mean something that would compel someone or something to moral behavior (as an oath might); later, it gained the two contradictory senses that refer to approval and economic disapproval. 

Occasionally, we can’t be sure why exactly a word develops auto-antonymous meanings. The alternate meanings of words like fast, dust, and weather can be explained by one meaning appearing earlier, or later, than the other. However, the exact mechanism of development is not clear.

How to deal with Janus words?

Luckily, the meaning of Janus words is usually clear from the context. You can easily understand the difference between ‘tied fast’ and ‘moving fast. You will rarely come across sentences that are completely ambiguous. 

However, if you are not sure, and come across an ambiguous sentence or an unfamiliar Janus word, it is always a good idea to double-check. Start with looking it up in a good English-English dictionary that will provide you with definitions of all the different meanings, as well as examples illustrating them. 

When trying to learn different meanings of Janus words, memorise or write them down with good clear examples that will help you evoke the meaning in the future. 

Final thoughts 

Words that can have two opposite meanings at the same time can seem confusing at first. However, they are not as scary as they seem. The meanings are usually clear from the context, and if you are in doubt, a dictionary can easily help you out. 

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