(painting, photography) An area or a spot in a drawing, painting, or photograph that is strongly illuminated.

(figurative) An especially significant or interesting detail or event or period of time.

(cosmetics) A strand or spot of hair dyed a different color than the rest.

(transitive) To make prominent; emphasize.

(transitive) To be a highlight of.

(transitive) To mark (important passages of text), e.g. with a fluorescent marker pen or in a wordprocessor, as a means of memory retention or for later reference.

(transitive) To dye (part of the hair) a different color than the rest.

(transitive, Internet) To seek the attention of (a user) on IRC by mentioning their name in a message, causing that message to appear highlighted on their screen.