labor vs labour

labor and labour both are nouns.

Word	Noun	Adjective	Verb	Adverb
labor	Yes	No	Yes	No
labour	Yes	No	Yes	No

As nouns, labor and labour are synonyms defined as:

labor and labour: productive work (especially physical work done for wages)

Other synonyms of labor include toil.

As nouns, labor and labour are synonyms defined as:

Other synonyms of labor include project, task, undertaking.

As nouns, labor and labour are synonyms defined as:

labor and labour: a social class comprising those who do manual labor or work for wages

Other synonyms of labor include proletariat, working class.

As nouns, labor and labour are synonyms defined as:

labor and labour: an organized attempt by workers to improve their status by united action (particularly via labor unions) or the leaders of this movement

Other synonyms of labor include labor movement, trade union movement.

As nouns, labor and labour are synonyms defined as:

labor and labour: concluding state of pregnancy; from the onset of contractions to the birth of a child

Other synonyms of labor include childbed, confinement, lying-in, parturiency, travail.

As verbs, labor and labour are synonyms defined as:

As verbs, labor and labour are synonyms defined as:

Other synonyms of labor include dig, drudge, fag, grind, moil, toil, travail.

As verbs, labor and labour are synonyms defined as:

Other synonyms of labor include drive, push, tug.

labor (noun)	labour (noun)
productive work (especially physical work done for wages)	productive work (especially physical work done for wages)
any piece of work that is undertaken or attempted	any piece of work that is undertaken or attempted
a social class comprising those who do manual labor or work for wages	a social class comprising those who do manual labor or work for wages
an organized attempt by workers to improve their status by united action (particularly via labor unions) or the leaders of this movement	an organized attempt by workers to improve their status by united action (particularly via labor unions) or the leaders of this movement
concluding state of pregnancy; from the onset of contractions to the birth of a child	concluding state of pregnancy; from the onset of contractions to the birth of a child

labor (verb)	labour (verb)
undergo the efforts of childbirth	undergo the efforts of childbirth
work hard	work hard
strive and make an effort to reach a goal	strive and make an effort to reach a goal