Meaning
A plain face with a downturned mouth, the simplest drawing of sadness. Like the classic ☺️ smiley, this is an older character that some apps show as a black outline unless the emoji style is requested, but the meaning is the same: unhappy, let down, a little sorry for yourself.
It covers everyday disappointments: “The café is closed today ☹️” It is stronger than the slightly frowning face yet far from crying, making it a good fit for honest but not dramatic sadness. Among friends it can also be a playful pout when plans fall through.