A propellant is a force or substance that drives something else forward. Your model rocket needs a propellant, or a fuel to push it into the air. You might use something as simple as vinegar and baking soda. Space rockets use solid or liquid propellants, or fuel.

Propellant derives from the word propel, which means to drive something forward with force. A propellant can be fuel, or the explosive charge that pushes a bullet out of a gun. Gases used to propel can be called "propellant gases" and might be stored in a "propellant tank." Note that some dictionaries accept the variant spelling propellent.

Definitions of propellant
  1. noun
    any substance that propels
    synonyms: propellent
    see moresee less
    rocket fuel, rocket propellant, rocket propellent
    an explosive charge that propels a rocket
    compressed gas
    gas at a high pressure that can be used as a propellant
    compressed air
    air at a pressure greater than that of the atmosphere
    type of:
    a particular kind or species of matter with uniform properties
  2. adjective
    tending to or capable of propelling
    propellant fuel for submarines”
    synonyms: propellent, propelling, propulsive
    dynamic, dynamical
    characterized by action or forcefulness or force of personality
Word Family

Test prep from the experts

Boost your test score with programs developed by’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week