mid-15c., "food made with or from paste or having it as a principal ingredient," not originally limited to sweets, from Middle English paste (see paste (n.)) + -ry. Probably influenced by Old French pastoierie "pastry" (Modern French pâtisserie), from pastoier "pastry cook," from paste (see paste (n.)); also borrowed from Medieval Latin pasteria "pastry," from Latin pasta. Specific sense of "small confection made of pastry" is by 1906. Pastry-cook is attested from 1650s.
c. 1300 (mid-12c. as a surname), "dough for the making of bread or pastry," from Old French paste "dough, pastry" (13c., Modern French pâte), from Late Latin pasta "dough, pastry cake, paste" (see pasta). Meaning "glue mixture, dough used as a plaster seal" is attested from c. 1400; broader sense of "a composition just moist enough to be soft without liquefying" is by c. 1600. In reference to a kind of heavy glass made of ground quartz, etc., often used to imitate gems, by 1660s.
c. 1300 (probably older; piehus "bakery" is attested from late 12c.), "baked dish of pastry filled with a preparation of meats, spices, etc., covered with a thick layer of pastry and baked," from Medieval Latin pie "meat or fish enclosed in pastry" (c. 1300), which is perhaps related to Medieval Latin pia "pie, pastry," also possibly connected with pica "magpie" (see pie (n.2)) on notion of the bird's habit of collecting miscellaneous objects.
According to the OED, the word is not known outside English with the exception of Gaelic pighe, which is from English. In the Middle Ages, a pie had many ingredients, a pastry but one. Fruit pies began to appear c. 1600.
The word in the figurative sense of "something easy" is from 1889. Slice of the pie in the figurative sense of "something to be shared out" is by 1967. Pie-eyed "drunk" is from 1904. Phrase pie in the sky is attested by 1911, from Joe Hill's Wobbly parody of hymns. Pieman "baker or seller of pies" is by c. 1300 as a surname. Pie chart is from 1922.
c. 1300, "a type of meat pie, a pie covered with paste or pie crust," especially one of venison or other seasoned meat, from Old French paste "dough, pastry," from Vulgar Latin *pastata "meat wrapped in pastry" from Latin pasta "dough, paste" (see pasta).
1706, "small pie or pastry," from French pâté, from Old French paste, earlier pastée, from paste (see paste (n.)). Especially pâté de foie gras (1827), which was originally a pie or pastry filled with fatted goose liver; the word now generally is used of the filling itself.