a small shallow dish for holding a cup at the table
"She carefully placed her teacup onto the matching saucer to avoid spilling any of the hot tea."
directional antenna consisting of a parabolic reflector for microwave or radio frequency radiation
"The technician adjusted the large satellite saucer to ensure the dish was perfectly aligned with the transponder beam."
A small shallow dish to hold a cup and catch drips.
"She carefully lifted the hot mug from its saucer so the warm water wouldn't spill on her desk."
To pour (tea, etc.) from the cup into the saucer in order to cool it before drinking.
"After blowing on her hot tea for a moment, she carefully poured some of it onto the saucer so it would be cooler to drink."