1.VerbTo buy a financial product, such as a share, so as to profit from a rise in its value; compare go short.
"I would recommend going long on tech stocks this year."
2.VerbTo run far from the person throwing a ball in order to receive a long pass; to run down the field away from the quarterback to receive a long or Hail Mary pass.
"He yelled to Steve "Go long!" just as the ball was snapped."
3.VerbUsed other than figuratively or idiomatically: see go, long.