Gravitational Lensing Definition

noun

The redirection or bending of light rays traveling in the gravitational field of an object, predicted by the general theory of relativity and commonly observed near massive objects like the sun, other stars, and distant galaxies.

American Heritage

(astronomy) The action of a star that acts as a gravitational lens and focusses starlight from another star that passes behind it as observed from the Earth.

Wiktionary