gloss
A smooth, shiny surface that reflects light.
Gloss is a smooth, shiny surface quality that makes something look polished and attractive. A freshly waxed car has a beautiful gloss, and so does a magazine cover or a well-maintained wooden floor. The word describes that gleaming, reflective quality that catches the light.
In another sense, gloss means a brief explanation or translation of a difficult word or phrase. When you're reading a challenging book and see a footnote explaining what an unfamiliar term means, that's a gloss. Teachers might provide glosses for Shakespeare's old-fashioned language to help students understand what the characters are really saying.
The word also appears in common phrases. To gloss over something means to skip past it quickly or treat it superficially, often because it's uncomfortable or inconvenient. If a student glosses over the hard parts of their homework, they're rushing through without really understanding. If a news report glosses over important details, it's leaving out information people need to know.
Lip gloss is a shiny cosmetic product, and glossy is the adjective form, describing anything with that smooth, shiny quality. A glossary is a mini-dictionary at the back of a textbook, listing specialized terms and their meanings.