mid-14c., piete (late 12c. as a surname), "mercy, tenderness, pity" (senses now obsolete in this word but preserved in its doublet, pity), from Old French piete "piety, faith; pity, compassion" (12c.), from Latin pietatem (nominative pietas) "dutiful conduct, sense of duty; religiousness, piety; loyalty, patriotism; faithfulness to natural ties," in Late Latin "gentleness, kindness, pity;" from pius "kind" (see pious).
From 1570s in English as "filial affection, dutiful conduct or behavior toward one's parents, relatives, country, etc." Meaning "piousness, faith in and reverence for the Supreme Being" is attested in English from c. 1600. Compare pity (n.).
1690s, in reference to a specific religious movement, Pietism, from German Pietismus, originally applied in derision to the movement to revive personal piety in the Lutheran Church, begun in Frankfurt c. 1670 by Philipp Jakob Spener (1635-1705). See piety + -ism. With lower-case p- and in reference generally to devotion, godliness of life (as distinguished from mere intellectual orthodoxy), by 1829.
c. 1300, pitous, "merciful, full of pity" (a sense now archaic; OED's last citation for it is in 1855); also "arousing or deserving pity, such as to excite compassion, lamentable, sorrowful," from Anglo-French pitous, Old French pitos, piteus "pious; merciful, compassionate, moved to pity; pitiful" (12c., Modern French piteux), from Medieval Latin pietosus "merciful, pitiful" (source also of Spanish piadoso), in Vulgar Latin "dutiful," from Latin pietas "dutiful conduct, compassion" (see piety). Also in Middle English "godly, righteous, devout, pious." With irregular development of form (according to OED the regular phonetic development from the French word would be *pitous). Related: Piteously; piteousness.
mid-13c., pite, "compassion, kindness, generosity of spirit;" c. 1300 "disposition to mercy, quality of being merciful," also "a feeling of sympathy and compassion aroused by the sorrow or suffering of another," from Old French pite, pitet "pity, mercy, compassion, care, tenderness; pitiful state, wretched condition" (11c., Modern French pitié), from Latin pietatem (nominative pietas) "piety, loyalty, duty" (see piety). Replaced Old English mildheortness, literally "mild-heartness," itself a loan-translation of Latin misericordia.
It is some comfort to receive commiseration or condolence ; it gives one strength to receive sympathy from a loving heart ; it is irksome to need compassion ; it galls us to be pitied. [Century Dictionary, 1895]
Middle English pity also could mean "devout obedience to God" (mid-14c.), and pity and piety were not fully distinguished until 17c. Transferred sense of "grounds or cause for pity, matter or source of grief or regret" is from late 14c.
1530s, "piety, devoutness, sanctity," a sense now obsolete, from French sanctimonie, from Latin sanctimonia "sacredness, holiness, virtuousness," from sanctus "holy" (see saint (n.)). The surviving sense of "external appearance of devoutness, hypocritical or affected piety" is by 1610s.
c. 1200, devocioun, "profound religious emotion, awe, reverence," from Old French devocion "devotion, piety" and directly from Latin devotionem (nominative devotio), noun of action from past-participle stem of devovere "dedicate by a vow, sacrifice oneself, promise solemnly," from de "down, away" (see de-) + vovere "to vow" (see vow (n.)). From late 14c. as "an act of religious worship, a religious exercise" (now usually devotions).
In ancient Latin, "act of consecrating by a vow," also "loyalty, fealty, allegiance;" in Church Latin, "devotion to God, piety." The application to secular situations came to English via Italian and French; sense of "act of setting apart or consecrating" is from c. 1500.
late 14c., religiosite, "religious feeling, reverence for God, piety," from Old French religiosete and directly from Late Latin religiositas "religiousness," from religiosus "pious, devout, reverencing or fearing the gods," also "religiously careful, anxious, or scrupulous" (see religious). In late 19c. especially "religious sentimentality, excessive susceptibility to religious emotion without corresponding regard for divine law."
c. 1200, of persons, "yielding reverential devotion to God," especially in prayer, "pious, religious," from Old French devot "pious, devoted, assiduous" (Modern French dévot) and directly from Latin devotus "given up by vow, devoted" (source also of Spanish and Portuguese devoto), past participle of devovere "dedicate by vow" (see devotion). Of actions, "expressing devotion or piety," late 14c. Meaning "sincere, solemn" is from mid-15c. Related: Devoutly; devoutness.