Things that pulsate throb with a regular, rhythmic beat — like the piped-in music at a trendy discotheque.
Music can pulsate, electromagnetic waves can pulsate, and your head can pulsate when you have a splitting headache. When someone takes your pulse by placing fingers on the inside of your wrist or on your neck, they're counting your heartbeats by feeling the blood pulsate through your arteries.