WordGarden.iounary
C2Pronunciation
UK
US
Meanings
Adjective
having one input, argument, component, or branch in a formal system
expressed in or using base 1, typically with repeated tally-like marks
Beyond the definition
Picture something that works with just one thing at a time. That is the heart of unary. In math, logic, and computer science, it describes an operation, operator, or system that involves exactly one item or one input. For example, the minus sign in "-5" is a unary operator because it acts on just one number. In the same way, an operation like "not" in logic also works on a single input.
The word comes from the Latin unus, meaning "one." You will mostly meet it in technical writing, especially in phrases like "unary operator" or "unary operation." People do not usually use it in everyday talk for general ideas like "single" or "alone"; it belongs more to precise, formal contexts.
The word "unary" comes from the Latin root unus, meaning "one." In modern English, it is mainly a technical word. It is used when something involves exactly one element, one argument, one operand, or one input. The idea is simple: if a process works on just one thing, it may be described as unary.
This is most common in mathematics, logic, and computer science. A unary operator acts on one value rather than two. For example, the minus sign in "-5" is unary because it changes a single number. The logical operator "not" is also unary because it flips one statement or truth value. This is different from binary operations like addition, comparison, or "and," which need two inputs. In grammar and formal systems, the word can also describe relations, functions, or predicates that apply to one item only.
You may also see the term in phrases like "unary numeral system" or "unary encoding." In that system, a number is shown by repeating one mark, so five can be written as five strokes. The idea is easy to grasp, even if it is not practical for large numbers.
Outside these formal and technical settings, English speakers rarely choose "unary" as a general synonym for "single" or "alone." That is the key point for natural usage: the word is correct when the context is mathematical, logical, grammatical, or computational, but it sounds unusual in ordinary everyday description. If binary means two and ternary means three, unary keeps the focus firmly on one.
Examples
- 1
Negative numbers
The calculator reads the minus sign in `-5` as unary, not as subtraction.
- 2
Programming
In Python, `not` is a unary operator, so it applies to just one value.
- Patternapply to + value
work on that value
- 3
Formal logic
In formal logic, negation is unary, while `and` and `or` are binary.
See also
Forms and spellings
1 form open this card.
Main spelling
- unaryadjective