To pulsate means to expand and contract rhythmically, like a steady beat or throb. Your heart pulsates as it pumps blood through your body: squeeze, release, squeeze, release, over and over in a reliable pattern. If you press your fingers to your wrist, you can feel your pulse, the pulsating rhythm of blood moving through your arteries with each heartbeat.

The word captures a sense of regular, wavelike movement. Music can seem to pulsate when the bass is so strong you feel it vibrating through your chest. Emergency vehicle lights pulsate as they flash on and off. The bioluminescent glow of certain jellyfish pulsates as they drift through dark ocean waters. Even a painful headache might feel like it's pulsating, throbbing in time with your heartbeat.

Scientists describe stars that rhythmically brighten and dim as pulsating stars. Whether it's the steady pulsation of a drum in a marching band or the throbbing sensation of an injured thumb after you've accidentally smashed it, pulsate describes that unmistakable feeling of rhythmic beating or throbbing.