English Reference
noun

constraint

n.
US /kənˈstɹeɪnt/ UK /kənstɹˈeɪnt/ con·straint UK spelling constraint's, constraint's

  1. 01 B2 Upper Intermediate

    something that limits your freedom to do what you want.

    a limitation or restriction on one's actions or choices. Often used in the plural to describe external pressures.

    Simple

    Financial constraints meant the family could not afford a holiday this year.

    In context

    The project was completed on time despite significant budgetary constraints and a shortage of skilled labour.

  2. 02 C1 Advanced Formal

    the act of hiding your true feelings or behaving in a very controlled way.

    the state of being checked or restricted in the expression of natural feelings or impulses.

    Simple

    They spoke to each other with great constraint after their argument.

    In context

    The diplomat maintained an air of polite constraint, refusing to let his personal frustrations show during the tense negotiations.

  3. 03 C1 Advanced Technical Math

    a condition or rule that a mathematical solution must follow.

    a condition that a solution to an optimization problem or a mathematical model must satisfy.

    Simple

    The engineer added a weight constraint to the design software.

    In context

    In linear programming, the feasible region is defined by the intersection of all given constraints within the model.

  4. 04 C1 Advanced Technical Computing

    a rule in a computer system that keeps data correct and organized.

    a rule or restriction enforced on data in a database to maintain integrity and consistency.

    Simple

    The database has a constraint that prevents two users from having the same ID.

    In context

    The developer implemented a foreign key constraint to ensure that every order was linked to a valid customer record.

Usage additional constraint · constraint limit · economic constraint

According to the researchers, the constraints imposed by childbirth require a relatively shallow pelvis and a sufficiently wide birth canal.

Phys.org· 17 Aug 2026

The researchers say changes in training delivery point to constraints in training pathways.

Phys.org· 17 Aug 2026

From Middle English constreynt, constreynte, from Old French constreinte, past participle of constreindre (“to constrain”), from Latin cōnstringō (corresponding to the past participle cōnstrictus).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin cōnstringō
Level C1 · Advanced
Frequency Frequent
Updated