- (uncountable, mathematics) A system for computation using letters or other symbols to represent numbers, with rules for manipulating these symbols.
- (uncountable, medicine, historical, rare) The surgical treatment of a dislocated or fractured bone. Also (countable): a dislocation or fracture.
- (uncountable, mathematics) The study of algebraic structures.
- (countable, mathematics) A universal algebra.
- (countable, algebra) An algebraic structure consisting of a module over a commutative ring (or a vector space over a field) along with an additional binary operation that is bilinear over module (or vector) addition and scalar multiplication.
- Synonyms: algebra over a field, algebra over a ring
- (countable, set theory, analysis) A collection of subsets of a given set, such that this collection contains the empty set, and the collection is closed under unions and complements (and thereby also under intersections and differences).
- Synonyms: field of sets
- (countable, mathematics) One of several other types of mathematical structure.
- (figurative) A system or process, that is like algebra by substituting one thing for another, or in using signs, symbols, etc., to represent concepts or ideas.