no-brainer

UK: /ˌnəʊˈbreɪ.nər/ | US: /ˌnoʊˈbreɪ.nɚ/

Definition
  1. n. something that requires little or no mental effort to understand or decide

  2. n. an extremely easy or obvious choice

Structure
no <negation>brain <mind>er <noun suffix>
Etymology

The term "no-brainer" emerged in mid-20th century American slang, combining "no" (negation) + "brain" (symbolizing mental effort) + "-er" (agentive suffix). It humorously implies a decision so simple that it "doesn’t require a brain." The word reflects colloquial efficiency, transforming abstract concepts (effortlessness) into vivid imagery.

Examples
  1. Choosing the cheaper option was a no-brainer.

  2. The math problem was a no-brainer for the gifted student.

  3. Investing in that startup seemed like a no-brainer at the time.

  4. "Should we take the shortcut?" "Yeah, it’s a no-brainer."

  5. The quiz had a few no-brainers to boost confidence.