noun (n)

• an impelling force or strength(noun.attribute)

  Example:
  The car's momentum carried it off the road.
  

  Synonym:
  impulse
  

  source: wordnet30
• the product of a body's mass and its velocity(noun.attribute)

  Example:
  The momentum of the particles was deduced from meteoritic velocities.
  

  source: wordnet30
• The quantity of motion in a moving body, being always proportioned to the quantity of matter multiplied into the velocity; impetus.(noun)

  source: webster1913