1.To open your awareness.
2.Something that just interest you or makes you happy.
Not just a sexual term. Anyone from the 60's used this term prevalently through out the grooviest time in our recent history.
Timothy Leary "Turn on, Tune in, drop out."
ex1: The warm weather today is such a turn on.
ex2:I just got Turned on by this guy to Jefferson Airplanes album.
A turn on is something that makes specific groups of people sexually stimulated ( horny ). Also known as fetishes, people have very different turn ons and while some may be music or clothes some people might like their sexual partner to be aggressive towards them during/before intercourse. The more dark and aggressive type of fetishes are called BDSM, which stands for Bondage, Discipline, Domination, Submission, Sadism and Masochism