English Reference
verb

assure

v.
US /əˈʃʊɹ/ UK /əʃjˈɔː/ as·sure UK spelling assures

  1. 01 B2 Upper Intermediate

    to tell someone that something is definitely true so they stop worrying.

    to inform someone positively or confidently to remove doubt. Transitive — typically takes a person as the direct object followed by a 'that' clause.

    Simple

    I can assure you that the plane will arrive on time.

    In context

    The doctor sought to assure the patient's family that the procedure was routine and carried minimal risk.

    Usage

    Usually follows the pattern: assure + person + that-clause.

    Pitfall
    I assure that the work is done. I assure you that the work is done.

    The verb 'assure' almost always requires a person as the direct object (the person you are talking to).

    alarmunsettle
  2. 02 B2 Upper Intermediate Academic

    to make sure that something happens or is true.

    to make certain or secure; to ensure a particular outcome.

    Simple

    We need to check the locks to assure the safety of the building.

    In context

    The new legislation was designed to assure equal access to healthcare for all citizens regardless of their income level.

    Usage

    In this sense, 'ensure' is often more common in modern American English, while 'assure' remains frequent in formal or British contexts.

Don't confuse

assure vs ensure vs insure — Assure is for people, ensure is for outcomes, and insure is for financial protection.

Meta, she said, went out of its way to "assure the public that its platforms were safe for kids".

BBC News· 18 Aug 2026

From Old French asseurer (Modern French assurer), from Latin ad- + securus (“secure”). Cognate with Spanish asegurar. Doublet of assecure.

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

This entry
Origin Latin ad-
Level B2 · Upper Intermediate
Frequency Common
Updated