The part of a software application that a user sees and interacts with.(noun)
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Use "user interface" in a sentence
"SOFTWARE EVOLUTION: THE COMMAND LINE INTERFACE Some of the earliest programs available for the AppleII had a user interface that was quite similar to the ones available for use with time-sharing terminals on mainframe computers: A command was typed on a line, and the computer would execute that command and return with a prompt for the next command."
"Bladelius to create a touch enabled user interface for Embla without compromise. ""