English Reference
noun · adjective

infrared

n. · adj.
US /ˌɪnfɹɝˈɛd/ UK /ˌɪnfɹəɹˈɛd/ in·frared UK spelling infrareds

  1. 01 B2 Upper Intermediate Technical Science

    n.a type of light that you cannot see, but you can feel it as heat.

    n.electromagnetic radiation with wavelengths between 700 nm and 1 mm, situated between the visible spectrum and microwaves.

    Simple

    The snake can find its prey in the dark by sensing infrared.

    In context

    The telescope captures infrared to peer through dense clouds of space dust that block our view of distant stars.

    Usage

    Often used as an uncountable noun when referring to the radiation itself.

    thermal radiation
  2. 02 B2 Upper Intermediate Technical Science

    adj.describes technology or light that uses the infrared part of the spectrum.

    adj.relating to or using electromagnetic radiation in the infrared spectrum.

    Simple

    You can use an infrared remote to change the TV channel.

    In context

    Security teams used infrared cameras to monitor the perimeter of the building during the blackout.

    Usage

    This adjective is non-gradable; something cannot be 'more infrared' than something else.

Usage infrared light

In our experiments, the cover allowed more than 60% of visible light to pass through on average while reflecting more than 80% of infrared light back at the sun.

Phys.org· 26 Aug 2026

All these telescopes had been outfitted with newly available infrared detectors.

The Conversation· 27 Aug 2026

From infra- + red.

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

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated