Know how to use "fewer" and "less"? Find out.
shout to call attention, 1781, earlier hollo, holla (see hello). Halow as a shipman's cry to incite effort is from mid-15c.; Halloo as a verb, "to pursue with shouts, to shout in the chase," from late 14c. Cf. also harou, cry of distress, late 13c., from French.