English

Alternative forms

• tin-foil hat

Noun

tinfoil hat ‎(plural tinfoil hats) (sometimes abbreviated TFH)

1. A piece of headgear made from one or more sheets of tin foil, aluminium foil, or other similar material, especially when worn in the belief that it shields the brain from electromagnetic fields, or against mind control and/or mind reading.
   • 2001 — Eoin Colfer, Artemis Fowl, p 42

     To prevent them from reading his mind, he wore a tinfoil hat at all times.

Derived terms

• tinfoil hatter
• tinfoilhattery