What does diffract mean?
To diffract is to cause waves — most commonly light, sound, or X-rays — to bend and spread out as they pass around an obstacle or squeeze through a narrow opening. The word belongs chiefly to the vocabulary of physics and engineering: optical instruments split light with diffraction gratings, and crystallographers determine molecular structures by diffracting X-rays off crystals and reading the resulting patterns. Yet the underlying idea is intuitive and observable in daily life — the iridescent sheen on a compact disc, the way sound reaches you even when the source is hidden behind a corner. Figuratively, diffract can suggest breaking something into fragments or diverting it from a direct path, though this sense is far less common than the technical one. Derived forms include "diffraction," "diffractive," and "diffractometer." For anyone interested in how waves behave — and why rainbows appear on the surfaces of everyday objects — diffract is an essential word.
To cause light, sound, or other waves to undergo diffraction — to bend and spread as they pass around an edge or through an opening.
"The electron beam was diffracted by the thin gold foil, producing rings of varying intensity."
Most frequently used transitively in technical contexts, e.g. "the grating diffracts the light."
Of a wave, to bend and spread out upon encountering an obstacle or aperture.
"Sound diffracts readily around large obstacles, which is why we hear around corners."
Every time you see the shimmering colors on a CD or a soap bubble, you're watching light being diffracted — physics painting with waves.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diffract
Diffract comes from Latin "diffringere" (also appearing as "diffract-"), meaning "to break in pieces," formed from the prefix "dis-" (apart) plus "frangere" (to break). English adopted the verb in the late 17th century as scientists began studying how light bends and spreads around obstacles. It shares its root "frangere" with words like fraction, fragment, refract, and fracture.
Related word forms
How diffract is actually used
"Diffract" is primarily a technical term used in physics, crystallography, optics, and acoustics. It appears most often in scientific writing and education rather than everyday conversation, though it occasionally carries figurative use when describing things scattering or bending away from a straight course.
Easily confused with diffract
Reflection bounces waves off a surface at an angle, whereas diffraction bends and spreads waves as they pass around edges or through openings.