A ray is a narrow beam of light, energy, or particles traveling in a straight line. When sunlight streams through your window in the morning, you might see bright rays cutting through the dust in the air. Scientists talk about X-rays that let doctors see your bones, or gamma rays from distant stars in space.

The word often appears in phrases like a ray of hope, meaning a small sign that things might get better, even when a situation looks grim. If your team is losing badly but suddenly scores, someone might say “that's a ray of hope.”

In geometry, a ray means something specific: a line that starts at one point and extends infinitely in one direction, like an arrow that never stops. Teachers use rays to explain angles and how light travels.

A ray is also a type of flat fish related to sharks, with wing-like fins and a long tail. Stingrays and manta rays glide gracefully through ocean water. These rays have skeletons made of cartilage instead of bone, just like their shark cousins.