To expand and contract rhythmically; to throb or to beat.
To quiver, vibrate, or flash; as to the beat of music.
To produce a recurring increase and decrease of some quantity.
Engage in rough-and-tumble activity
An environment of rough activity
Rough activity; fighting or brawling; a fight.
A person who characteristically engages in such activity
active, vigorous and rough, with the possibility of harm
highly competitive