"sloping timber of a roof," c. 1200, from Old English ræftras (West Saxon), reftras (Mercian), both plural, "a beam, pole, rafter of a building," related to Old Norse raptr "log," from Proto-Germanic *raf-tra-, from PIE *rap-tro-, from root *rep- "stake, beam."
also dormer-window, "window standing vertically in a projection built out to receive it from a sloping roof," 1590s, from French dormeor "sleeping room," from dormir "to sleep," from Latin dormire (see dormant). So called because they were chiefly in upper bedrooms.
in architecture, a type of vault or small dome, 1540s, from Italian cupola, from Late Latin cupula "a little tub," diminutive of Latin cupa "cask, barrel" (see cup (n.)). Hence "the rounded top of any structure."
The Italian word signifies a hemispherical roof which covers a circular building, like the Pantheon at Rome or the temple of Vesta at Tivoli. Most modern cupolas are semi-elliptical, cut through their shortest diameter; but the greater number of ancient cupolas were hemispherical. In colloquial use, the cupola is often considered as a diminutive dome, or the name is specifically applied to a small structure rising above a roof and often having the character of a tower or lantern, and in no sense that of a dome. [Century Dictionary, 1897]
"part of the human body where pelvis and thigh join," Old English hype "hip," from Proto-Germanic *hupiz (source also of Dutch heup, Old High German huf, German Hüfte, Swedish höft, Gothic hups "hip"), of uncertain origin. In architecture, "external angle at the junction of two sides of a roof," from late 17c. Hip-flask, one meant to fit in a hip pocket, is from 1923. Related: Hips.
"curved like a circle or sphere when viewed from outside," 1570s, from French convexe, from Latin convexus "vaulted, arched," past participle of convehere "to bring together," from assimilated form of com "with, together," or "thoroughly" (see com-) + vehere "to bring, carry, convey" (from PIE root *wegh- "to go, move, transport in a vehicle").
Possibly the notion is of vaults "carried together" to meet at the point of a roof. Related: Convexity. Convex lens is from 1822.
"end of a ridged roof cut off in a vertical plane, together with the wall from the level of the eaves to the apex," mid-14c., "a gable of a building; a facade," from Old French gable "facade, front, gable," from Old Norse gafl "gable, gable-end" (in north of England, the word probably is directly from Norse), according to Watkins, probably from Proto-Germanic *gablaz "top of a pitched roof" (source also of Middle Dutch ghevel, Dutch gevel, Old High German gibil, German Giebel, Gothic gibla "gable"). This is traced to a PIE *ghebh-el- "head," which seems to have yielded words meaning both "fork" (such as Old English gafol, geafel, Old Saxon gafala, Dutch gaffel, Old High German gabala "pitchfork," German Gabel "fork;" Old Irish gabul "forked twig") and "head" (such as Old High German gibilla, Old Saxon gibillia "skull"). See cephalo-.
Possibly the primitive meaning of the words may have been 'top', 'vertex'; this may have given rise to the sense of 'gable', and this latter to the sense of 'fork', a gable being originally formed by two pieces of timber crossed at the top supporting the end of the roof-tree. [OED]
Related: Gabled; gables; gable-end.
Middle English roste, "a chicken's perch," from late Old English hrost "wooden framework of a roof; pole or perch upon which domestic fowl perch or rest for the night," from Proto-Germanic *hro(d)-st- (source also of Old Saxon hrost "framework of a roof, attic," Middle Dutch, Flemish, Dutch roest "roost," Old Norse hrot, Gothic hrot "roof"), a word of unknown origin. Extended sense "hen-house" is from 1580s; that of "fowls which occupy the roost collectively" is by 1827.
To rule the roost is recorded from 1769, according to OED apparently an alteration of earlier rule the roast "be the master, have authority " (c. 1500), which, OED reports, was "In very common use from c 1530 onwards." However, Fowler (1926) has doubts: "most unliterary persons say roost & not roast ; I have just inquired of three such, & been informed that they never heard of rule the roast, & that the reference is to a cock keeping his hens in order. Against this tempting piece of popular etymology the OED offers us nothing more succulent than "None of the early examples throw any light on the precise origin of the expression'." The spelling in the earliest example is reule the roste.
"sea-robber, pirate," late 14c. (c. 1300 as a surname), from Middle Dutch rover "robber, predator, plunderer," especially in zeerovere "pirate," literally "sea-robber," from roven "to rob," from Middle Dutch roof "spoil, plunder," related to Old English reaf "spoil, plunder," reafian "to reave" (see reave (v.), and compare reaver).
"building whose rafters lean against another building or wall," mid-15c., from lean (v.) + to (adv.). Compare penthouse. "An addition made to a house behind, or at the end of it, chiefly for domestic offices, of one story or more, lower than the main building, and the roof of it leaning against the wall of the house" [Bartlett].