What’s the opposite of disgruntled? Chances are you’re thinking the answer should rightly be gruntled—but is that really a word you recognize? The problem here is that disgruntled, alongside the likes of uncouth, disheveled, distraught, inert, and intrepid, is an example of an unpaired word, namely one that looks like it should have an apparently straightforward opposite, but in practice really doesn’t.
Words like these tend to come about either when a prefixed or suffixed form of a word is adopted into the language while its root is not, or when the inflected or affixed form of a word survives, while its uninflected root form falls out of use. This was the case with disgruntled, which derives from an ancient Middle English word, gruntel, meaning “to grumble” or “complain,” which has long since fallen from use—although the gap left by disgruntled has led some dictionaries to list gruntled as a modern-day back-formation.

2. ANONYMOUS
Anonymous literally means “without a name.” Its opposite is onymous, which is typically used to refer to books, legal papers, artworks, musical compositions, and similar documents the authorship of which is known without doubt.
3. AUTOMATON
If an automaton is a machine capable of moving itself, then the opposite is called a heteromaton—a device that relies solely on external forces for movement.
4. CATASTROPHE
If a catastrophe is a sudden, unpredictable, and devastating event, then an equally sudden or unexpected event of sheer joy or good fortune is a eucatastrophe. This term was coined by Lord of the Rings author JRR Tolkien in 1944, who originally used it to describe a sudden or fortuitous event in the plot of a story that turns around the protagonist’s chances or prospects, and brings about the resolution of the narrative.
5. DÉJÀ VU
Over the years, psychologists have identified a number of different phenomena similar to déjà vu (literally “already seen” in French). Among them is presque vu (“almost seen”), the tip-of-the-tongue feeling that you’re about to remember something you’ve forgotten; déjà vécu (“already experienced”), a particularly intense form of déjà vu that makes it almost impossible to discern the present from the past; and déjà visité (“already visited”), which describes a person’s surprising foreknowledge of a place they’ve never actually been to before—like unthinkingly knowing your way around a foreign town or city while on holiday. The opposite of déjà vu, however, is usually said to be jamais vu (“never seen”): so if déjà vudescribes the eerie sensation that something new has actually taken place before, in the case of jamais vu a person believes that a situation that is actually very familiar and has happened before is entirely new.
7. EUPHEMISM
If a euphemism involves the use of a politer word or phrase in place of a more distasteful or objectionable one, a dysphemism is the deliberate use of an impolite or unpleasant term in place of a perfectly inoffensive one. Dysphemism is often used for rhetorical effect, in order to shock or shake up an audience, or simply for comic effect.
10. POSTPONE
To bring a date forward in time rather than postponing it is to prepone it.