English Reference
noun

backbone

n.
US /ˈbækˌboʊn/ UK /bˈækbəʊn/ back·bone UK spelling backbone's, backbone's

  1. 01 B2 Upper Intermediate Medicine

    the row of bones that goes down the middle of your back.

    the series of vertebrae extending from the skull to the pelvis, forming the main support of the body.

    Simple

    The doctor checked the curve of his backbone to see if it was straight.

    In context

    The injury to his backbone was severe enough to require several months of intensive physical therapy and specialized bracing.

    Usage

    Often used as a synonym for 'spine' in both medical and general contexts.

    spinespinal columnvertebrae
  2. 02 B2 Upper Intermediate

    the most important part of a system or organization that gives it strength.

    the chief support or fundamental structural component of an organization, system, or infrastructure.

    Simple

    Small businesses are the backbone of the local economy.

    In context

    The high-speed fiber-optic cables form the backbone of the national telecommunications network, carrying the vast majority of data traffic.

    Usage

    Frequently used in the phrase 'the backbone of' followed by a noun phrase.

  3. 03 C1 Advanced Informal

    the strength of character to do what is right, even when it is difficult.

    strength of character, resolve, or moral courage. Uncountable in this sense.

    Simple

    He didn't have the backbone to tell his boss that he was quitting.

    In context

    The board of directors lacked the backbone to stand up to the CEO, even when the company's ethical standards were clearly being compromised.

    Teacher's tip

    This sense is often used in negative constructions to criticize someone for being weak or indecisive.

Data centers also need to be close enough to users and network backbones to provide fast digital services.

ScienceDaily· 19 Jun 2026

From Middle English bakbon, bakebon, bac-bon; equivalent to back + bone. Compare the semantically analogous English ridgebone.

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

This entry
Origin Middle English bakbon
Level B2 · Upper Intermediate
Frequency Frequent
Updated