c. 1300, "mountain top, sharp peak, promontory," from Old French pinacle "top, gable" (13c.) and directly from Late Latin pinnaculum "peak, pinnacle, gable," extended form (via diminutive suffix, but not necessarily implying smallness) of Latin pinna "peak, point," (see pin (n.)). Figurative use is attested from c. 1400. The meaning "pointed turret on the buttress or roof of a building" is from late 14c.

Its constructive object is to give greater weight to the member which it crowns, in order that this may better resist some lateral pressure. The application of the term is generally limited to an ornamental spire-shaped structure, standing on parapets, angles, and buttresses, and often adorned with rich and varied devices. [Century Dictionary]

1550s, "a tuft or plume of feathers," especially as worn in a hat or helmet, from French pennache "tuft of feathers," from Italian pennaccio, from Late Latin pinnaculum "small wing, gable, peak" (see pinnacle). Figurative sense of "display, swagger" is recorded from 1898 (in translation of "Cyrano de Bergerac"), from French.

Also petə-, Proto-Indo-European root meaning "to rush, to fly." 

It forms all or part of: accipiter; appetence; appetite; apterous; apteryx; archaeopteryx; asymptote; centripetal; Coleoptera; compete; competent; eurypterid; feather; helicopter; hippopotamus; Hymenoptera; impetigo; impetuous; impetus; iopterous; Lepidoptera; ornithopter; panache; panne; pen (n.1) "writing implement;" pennon; peripeteia; perpetual; perpetuity; petition; petulance; petulant; pin; pinion; pinnacle; pinnate; pinniped; potamo-; potamology; propitiation; propitious; ptero-; pterodactyl; ptomaine; ptosis; repeat; symptom.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pattram "wing, feather, leaf," patara- "flying, fleeting;" Hittite pittar "wing;" Greek piptein "to fall," potamos "river, rushing water," pteron, pteryx "feather, wing," ptilon "soft feathers, down, plume;" Latin petere "to attack, assail; seek, strive after; ask for, beg; demand, require," penna "feather, wing;" Old Norse fjöðr, Old English feðer "feather;" Old Church Slavonic pero "feather;" Old Welsh eterin "bird."

also zikkurat, 1858, from Assyrian ziqquratu "height, pinnacle," from zaqaru "to be high."

mid-14c., from Old English tind "spike, beak, prong, tooth of a fork," a general Germanic word (compare Old High German zint "sharp point, spike," Old Norse tindr "tine, point, top, summit," German Zinne "pinnacle"), of unknown origin (see zinc).

early 14c., croket, "ornamental roll or lock of hair," from Anglo-French crocket, from northern French form of Old French crochet, croquet, literally "a hook" (see crochet (n.)). In medieval architecture, "pointed ornamental device on a sloping pinnacle, gable, etc.," late 14c. Related: Crocketed.

1640s, Greek, Areios pagos "the hill of Ares," west of the Acropolis in Athens, where the highest judicial court sat. The second element is from pagos "pinnacle, cliff, rocky hill," related to pegnunai "to fasten, coagulate" (from PIE root *pag- "to fasten"). The sense was extended to any important tribunal.

"small wheel with teeth to gear with a larger one" (as in rack and pinion), 1650s, from French pignon "pinion" (16c.), literally "a gable," from Old French pignon "pointed gable, summit," from Vulgar Latin *pinnionem, augmentative of Latin pinna "battlement, pinnacle" (see pin (n.)). Pinoun as "a gable" was borrowed from Old French in Middle English (late 13c.).

large, deep-built vessel used for trading but fitted for fighting, late 14c., from Old French caraque "large, square-rigged sailing vessel," from Spanish carraca, related to Medieval Latin carraca, Italian caracca, all of uncertain origin, perhaps from Arabic qaraqir, plural of qurqur "merchant ship." The Arabic word itself perhaps was from Latin carricare "to load a car" (see charge (v.)) or Greek karkouros "boat, pinnacle."

also neo-paganism, "a revival or reproduction of paganism," 1858; see neo- "new" + paganism. Related: Neopagan (1854 as an adjective, 1855 as a noun).

[The 'positive' philosopher of the present day] offers in the stead of Christianity a specious phase of neo-paganism, by which the nineteenth century after Christ may be assimilated to the golden age of Mencius and Confucius; or, in other words, may consummate its intellectual freedom, and attain the highest pinnacle of human progress, by reverting to a state of childhood and of moral imbecility. [Introduction to Charles Hardwick, "Christ and Other Masters," Cambridge, 18758]