The root puls means “to drive” or “to push.” It comes from Latin, specifically from the verb pellere, meaning to push, drive, or strike. The form puls entered English through pulsus, the past participle of that verb, and it traces back even further to an ancient Proto-Indo-European root meaning “to thrust, strike, drive.” You’ll find it hiding inside dozens of common English words, from “impulse” to “expulsion,” and once you know what it means, those words start making a lot more sense.
How Puls and Pel Are Related
Latin verbs have different stems depending on their grammatical form, which is why this single root shows up in English in two guises: puls and pel. The pel form comes from the present tense of pellere and appears in words like “repel,” “propel,” and “compel.” The puls form comes from the past participle pulsus and appears in words like “repulse,” “impulse,” and “compulsion.” Both carry the same core meaning of pushing or driving. If you see either puls or pel in an English word, you’re looking at the same Latin idea wearing different grammatical clothes.
Common English Words Built on Puls
The easiest way to understand this root is to see how prefixes change its direction. Each prefix tells you where or how the pushing happens.
- Impulse (im- = into): a drive pushing into you from within. A sudden impulse is literally an inward push toward action.
- Repulse / Repel (re- = back): to push something back or away. Something repulsive drives you away from it.
- Expulsion / Expel (ex- = out): to push or drive out. A student expelled from school has been driven out of it.
- Compulsion / Compel (com- = together, with force): to push someone forcefully toward something. Feeling compelled means being driven by pressure to act.
- Propel (pro- = forward): to push forward. A propeller drives a boat or plane ahead.
- Pulsate: to beat or throb repeatedly, one push after another.
- Dispel (dis- = apart): to push apart or scatter. You dispel a myth by driving it away.
Notice the pattern: every one of these words describes some kind of pushing, driving, or forcing. The prefix simply tells you the direction.
Why Your Heartbeat Is Called a Pulse
The word “pulse” itself is one of the oldest English borrowings from this root, appearing in the early 1300s. It came through Old French pous and directly from Latin pulsus venarum, which literally meant “a beating from the blood in the veins.” Your heart pushes blood outward with each contraction, and that rhythmic push is what you feel when you press your fingers to your wrist. The radial pulse at your wrist remains one of the simplest tools in medicine for checking heart rate, rhythm, and even the strength of each beat. A strong, bounding pulse suggests the heart is pushing a large volume of blood per beat. A weak, low-volume pulse can suggest the opposite. The entire concept ties back to that original Latin meaning: a repeated drive or push.
The Root in Science and Technology
Beyond medicine, the idea of a “pulse” as a single push or burst shows up throughout physics and engineering. In physics, a pulse is an individual disturbance that travels through a medium, whether that’s a ripple moving along a rope, a burst of sound through air, or a flash of electromagnetic radiation through a vacuum. The concept is always the same: one discrete push moving outward through space. Electrical engineers talk about pulse signals, laser physicists study light pulses, and radio operators send pulse transmissions. In every case, the word points back to a single, defined push of energy.
Spotting the Root in Unfamiliar Words
Knowing that puls and pel mean “to push or drive” gives you a reliable tool for decoding unfamiliar vocabulary. If you encounter the word “propulsive,” you can break it apart: pro (forward) + puls (push) + ive (having the quality of). Something propulsive has a forward-driving quality. “Compulsory” breaks down the same way: com (with force) + puls (push) + ory (relating to). Something compulsory pushes you to do it, meaning it’s required.
This works with less common words too. “Appellation” doesn’t come from this root (it’s from a different Latin verb), but “appellant” in some historical usages and “interpellation” do involve the idea of driving or directing. The key test is whether the word contains puls or pel in a context that involves motion, force, or pressure. If it does, you’re almost certainly looking at a descendant of Latin pellere.