1610s, "word of honor," especially "promise by a prisoner of war not to escape if allowed to go about at liberty, or not to take up arms again if allowed to return home," from French parole "word, speech" (in parole d'honneur "word of honor") from Vulgar Latin *paraula "speech, discourse," from Latin parabola "comparison," from Greek parabole "a comparison, parable," literally "a throwing beside," hence "a juxtaposition" (see parable). Sense of "conditional release of a prisoner before full term" is attested by 1908 in criminal slang.
