Syncope (SINK-a-pee) is another word for fainting or passing out. Someone is considered to have syncope if they become unconscious and go limp.

Pre-syncope is the feeling that you are about to faint. Someone with pre-syncope may be lightheaded (dizzy) or nauseated, have a visual "gray out" or trouble hearing, have palpitations, or feel weak or suddenly sweaty.