WordNet sense 1 (concluding state of pregnancy; from the onset of labor to the birth of a child):

confinement, labor, lying-in, travail, childbed, parturiency

WordNet sense 2 (a political party formed in Great Britain in 1900; characterized by the promotion of labor's interests and the socialization of key industries):

labor party, Labour Party

WordNet sense 3 (a social class comprising those who do manual labor or work for wages):

proletariat

WordNet sense 4 (work hard):

dig, drudge, grind, moil, toil

WordNet sense 5 (strive and make an effort to reach a goal):

drive, push, tug