The Collaborative International Dictionary of English v.0.48:

Herdman \Herd"man\, Herdsman \Herds"man\, n.; pl. -men.
   The owner or keeper of a herd or of herds; one employed in
   tending a herd of cattle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

herdsman
    n 1: someone who drives a herd [syn: herder, herdsman,
         drover]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "herdsman":
   Gyropilot, automatic pilot, boatheader, boatsteerer, cattleman,
   cicerone, courier, cowboy, cowgirl, cowhand, cowherd, cowman,
   cowpuncher, coxswain, dragoman, drover, gaucho, goatherd, gooseboy,
   gooseherd, guide, guidepost, guider, helmsman, herd, herder,
   hogherd, horse wrangler, horseherd, mercury, navigator, pigman,
   pilot, pointer, puncher, river pilot, sheepherder, sheepman,
   shepherd, shepherdess, steerer, steersman, swanherd, swineherd,
   tour director, tour guide, vaquero, waddy, wrangler



Easton's 1897 Bible Dictionary:

Herdsman
   In Egypt herdsmen were probably of the lowest caste. Some of
   Joseph's brethren were made rulers over Pharaoh's cattle (Gen.
   47:6, 17). The Israelites were known in Egypt as "keepers of
   cattle;" and when they left it they took their flocks and herds
   with them (Ex. 12:38). Both David and Saul came from "following
   the herd" to occupy the throne (1 Sam. 9; 11:5; Ps. 78:70).
   David's herd-masters were among his chief officers of state. The
   daughters also of wealthy chiefs were wont to tend the flocks of
   the family (Gen. 29:9; Ex. 2:16). The "chief of the herdsmen"
   was in the time of the monarchy an officer of high rank (1 Sam.
   21:7; comp. 1 Chr. 27:29). The herdsmen lived in tents (Isa.
   38:12; Jer. 6:3); and there were folds for the cattle (Num.
   32:16), and watch-towers for the herdsmen, that he might
   therefrom observe any coming danger (Micah 4:8; Nah. 3:8).