(mathematics, computing) A function or other mapping that carries variables defined on a domain into another variable; operator.

untie; unravel; undo (a fastening); unwrap / dispel (doubts); clear up (a matter)

solve (a problem); answer (a question); unravel (a riddle) / comb; untangle (hair)

(uncommon, dialect) factual, true, correct, accurate / (uncommon, dialect) genuine, real / (uncommon, dialect) actual, real, certain

to use / to employ / to make use of, to apply / to spend

(physically) true, straight, unwarped, unskewed, proper / (abstractly) correct, right, true

need, necessity

needed, necessary

mathematics (field of study)

(arithmetic) arithmetic operator