gather momentum/strength

: to bring together : collect

: pick, harvest

: to pick up or amass as if by harvesting

: something brought together: such as

: a puckering in cloth made by gathering (see ¹gather 7a)

: a mass of molten glass collected for use in glassblowing

: a property (see property 1a) of a moving body that the body has by virtue of its mass (see ²mass 1c) and motion and that is equal to the product of the body's mass and velocity

: strength or force gained by motion or by a series of events

: the quality or state of being strong : capacity for exertion or endurance

: power to resist force : solidity, toughness

: power of resisting attack : impregnability