front end

n. 1. An intermediary computer that does set-up and filtering for another
(usually more powerful but less friendly) machine (a back end ). 2. What
you're talking to when you have a conversation with someone who is making
replies without paying attention. Look at the dancing elephants! Uh-huh. Do
you know what I just said? Sorry, you were talking to the front end. 3.
Software that provides an interface to another program behind it, which may
not be as user-friendly. Probably from analogy with hardware front-ends (see
sense 1) that interfaced with mainframes.