WordNet sense 1 (the time at which something is supposed to begin):

beginning, commencement, first, kickoff, offset, outset, get-go, showtime, starting time

WordNet sense 2 (a line indicating the location of the start of a race or a game):

starting line

WordNet sense 3 (a signal to begin (as in a race)):

starting signal

WordNet sense 4 (advantage gained by an beginning early (as in a race)):

head start

WordNet sense 5 (have a beginning characterized in some specified way):

begin

WordNet sense 6 (begin work or acting in a certain capacity, office or job):

take up

WordNet sense 7 (bulge outward):

bulge, pop, protrude, pop out, come out, bug out, bulge out

WordNet sense 8 (leave):

depart, part, set forth, take off, set off, set out, start out

WordNet sense 9 (move or jump suddenly, as if in surprise or alarm):

jump, startle

WordNet sense 10 (begin or set in motion):

go, get going

WordNet sense 11 (get off the ground):

commence, embark on

WordNet sense 12 (bring into being):

initiate, originate, initiate

WordNet sense 13 (set in motion, cause to start):

lead off

WordNet sense 14 (take the first step or steps in carrying out an action):

get, set about, get down

WordNet sense 15 (a turn to be a starter (in a game at the beginning)):

starting