dual
- 01 B2 Upper Intermediate
adj.having two parts, or having two different purposes at the same time.
adj.consisting of two parts, elements, or aspects; often used to describe a single entity with two distinct functions.
Simple“The new laptop has a dual purpose as both a computer and a tablet.”
In context“The candidate holds dual citizenship, which complicates the security clearance process for the high-level government position.”
UsageUsually placed before the noun it modifies.
- 02 C1 Advanced
adj.a special form of a word used in some languages to talk about exactly two people or things.
adj.pertaining to a grammatical number that specifically denotes two of a kind, distinct from singular and plural.
Simple“Some ancient languages have a dual form for pairs like eyes or hands.”
In context“While Modern English relies on the plural, Old English utilised a dual number for the first and second person pronouns.”
UsageUsed as a technical descriptor for morphological categories.
- 03 C2 Proficiency
adj.describing a relationship where two things are opposites but also match each other perfectly.
adj.relating to duality, where one mathematical structure or physical theory can be translated into another.
Simple“The scientist explained the dual nature of light as both a particle and a wave.”
In context“In projective geometry, every theorem has a dual statement where the roles of points and lines are interchanged.”
Synonyms - 04 C2 Proficiency
n.one of two things that form a pair, especially in math or logic.
n.an object, property, or proof that exists in a relationship of duality with another.
Simple“The cube is the dual of the octahedron.”
In context“To solve the optimisation problem, the student first had to derive the dual of the original linear programme.”
Synonyms - 05 C1 Advanced
v.to change a road with one lane in each direction into a larger road with two lanes in each direction.
v.to convert a single-carriageway road into a dual carriageway.
Simple“The government plans to dual the main highway to reduce traffic jams.”
In context“The local council has finally secured the funding required to dual the bypass, a project expected to take eighteen months.”
UsageThis is a transitive verb, typically used in civil engineering or urban planning contexts.
Usage dual effect · dual purpose · dual role
“Three British nationals, a Palestinian, a Pole and a dual US-Canadian citizen were also killed in the attack.”
“The president also suggested that his new helipad will be dual use, also serving as a second patio.”
PIE word *dwóh₁ Borrowed from Latin dualis (“two”), from duo (“two”) + adjective suffix -alis.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.