A group of words starting with the same letter is called?

shoe, spit, spider, spell, spout, sprout, spike, spiky, spill, spin, splurg, spun, spot, sport, sill, silk, save, shack, shaft, shell, shift, shoot, shot, ship, shirt, shave, shape, shark, shelf, sheet, sheek, shuck, start, stable, staff, still, stark, strike, strife, stripe, strap, street, stroke, stop, stove, stout, stow, snow, snipe, sneed, snark, snake, snail, subistute, substrate, settings, science, save, sat, saturated, sap, satin, sack, sail, saphire ....... there are man more but im to lazy to think of more :P