c. 1200, ypocrite, "false pretender to virtue or religion," from Old French ypocrite (12c., Modern French hypocrite), from Church Latin hypocrita "a hypocrite," from Greek hypokritēs "stage actor; pretender, dissembler," from hypokrinesthai (see hypocrisy).
"one who conceals his opinions, character, etc., under a false appearance, one who pretends that a thing which is is not," 1520s, agent noun from dissemble. "A dissembler is one who tries to conceal what he is; a hypocrite, one who tries to make himself appear to be what he is not, especially to seem better than he is." [Century Dictionary]
"member of an ancient Jewish sect (2c. B.C.E.-1c. C.E.) distinguished by strict observance but regarded as pretentious and self-righteous," at least by Jesus (Matthew xxiii.27), c. 1200, Pharise, from Old English Fariseos, Old French pharise (13c.), and directly from Late Latin Pharisæus, from Greek Pharisaios, from Aramaic (Semitic) perishayya, emphatic plural of perish "separated, separatist," corresponding to Hebrew parush, from parash "he separated." Extended meaning "any self-righteous person, formalist, hypocrite, scrupulous or ostentatious observer of the outward forms of religion without regard to its inward spirit" is attested from 1580s.
in reference to opposite aspects of a person's character is a reference to Robert Louis Stevenson's story, "The Strange Case of Dr. Jekyll and Mr. Hyde," published in 1886. Jekyll, the surname of the respectful and benevolent man, is of Breton origin and was originally a personal name. Hyde in reference to the dark, opposite side of one's personality is from 1887.
"Though so profound a double-dealer, I was in no sense a hypocrite. Both sides of me were in dead earnest; I was no more myself when I laid aside restraint and plunged in shame, than when I labored, in the eye of day, at the furtherance of knowledge or the relief of sorrow and suffering." [Robert Louis Stevenson, "The Strange Case of Dr. Jekyll and Mr. Hyde," 1886]
Earliest French use of the word is as the name of a people apparently in southern Gaul, which led to the theory, now considered doubtful on phonetic grounds, that the word comes from Visigothus. The typical use in Old French seems to have been as a derogatory nickname for Normans, leading to another theory (not universally accepted) that traces it to the Normans' (alleged) frequent use of the Germanic oath bi God. OED dismisses in a three-exclamation-mark fury one fanciful version of the "by god" theory as "absurdly incongruous with facts." At the end, not much is left standing except Spanish bigote "mustache," which also has been proposed as the origin of the word, but not explained, so the chief virtue of that theory is the lack of evidence for or against it.
In support of the "by God" theory the surnames Bigott, Bygott are attested in Normandy and in England from the 11c., and French name-etymology sources (such as Dauzat) explain it as a derogatory name applied by the French to the Normans and representing "by god." The English were known as goddamns 200 years later in Joan of Arc's France, and during World War I Americans serving in France were said to be known as les sommobiches (see son of a bitch) for their characteristic oaths. But the sense development in bigot would be difficult to explain. According to Donkin, the modern use first appears in French in 16c. This and the earliest English sense, "religious hypocrite," especially a female one, might have been influenced by or confused with beguine (q.v.) and the words that cluster around it.