A Leaflet

1. (botany) One of the components of a compound leaf.
2. (botany) A small plant leaf. Leaflet (botany) - Wikipedia

Synonym: leafling

3. A small sheet of paper containing information, used for dissemination of said information, often an advertisement. Synonyms: flyer, folder, handbill, pamphlet
4. (anatomy) A flap of a valve of a heart or blood vessel.