Momentum is traditionally defined as "the quantity of motion," but alternative definitions include "mass in motion" and "the impetus of a body resulting from its motion." The discussion emphasizes the importance of relating momentum to mass and velocity, as well as understanding its physical implications. Participants suggest that a deeper understanding of momentum may be more valuable than simply memorizing definitions. The context of the question appears to focus on demonstrating comprehension rather than rote learning. Overall, exploring various definitions can enhance one's grasp of the concept of momentum.