Old English ribb "a rib; one of a series of long, slender, curved bones of humans and animals, forming a kind of cage or partial enclosure for the chief organs," from Proto-Germanic *rebjan (source also of Old Norse rif, Old Saxon ribbi, Old Frisian rib, reb, Middle Dutch, Dutch ribbe, Old High German ribba, German Rippe).

Boutkan finds the old derivation of this from PIE *rebh- "to roof, cover" (on the notion of "a covering" of the cavity of the chest) doubtful, "particularly because the alleged semantic development to 'rib' is found only in Gmc. and Slavic."

Cookery sense of "piece of meat from an ox, pig, etc. containing one or more ribs" is from early 15c. As "a ship's curved frame timber" from 1550s.

Rib-roast "joint of meat for roasting which includes one or more ribs" is by 1889. Rib-eye for a cut of meat that lies along the outer side of a rib is by 1926, American English, with eye in a specialized sense in butchery. Rib joint "brothel" is slang from 1943, probably in reference to Adam's rib (compare rib "woman, wife," attested from 1580s).

"to dupe, tease, fool," by 1930, apparently from rib (n.), which is attested by 1929 in a slang sense of "a joke,"  perhaps a figurative use of poking someone in the ribs (rib-digging "light-heated banter" is attested by 1925).

Earlier it meant "to plow land so as to leave a space between furrows (1735) and "to clean (flax) with a rib" (early 14c.), a special tool for that job, which is probably an extended sense of rib (n.). Compare Middle Low German ribbeisern ("rib-iron"), a tool for cleaning flax. Related: Ribbed; ribbing.

also ribband, in ship-building, "long, flexible timber extending the length of the vessel body and nailed or bolted around the ribs to hold them in position," 1711, from rib (n.) + band (n.1).

1776, originally of land, "having rocky rib-like ridges;" figurative sense of "resolute" is recorded by 1887; see rock (n.) + rib (n.). 

"low, narrow rock ridge underwater," 1580s, riffe, probably via Dutch riffe, from a Scandinavian source such as Old Norse rif "ridge in the sea; reef in a sail," literally "rib" (see rib (n.)). Also extended to the low islands formed by coral debris or to any extensive elevation of the bottom of the sea.

"horizontal section of sail rolled or folded" to reduce the area exposed to the wind, late 14c., rif (mid-14c. in rif-rope "rope used in tying down a reef"), from a Scandinavian source such as Old Norse rif "reef of a sail," probably a transferred use of rif "ridge under the sea; rib" (see rib (n.) and compare reef (n.1)). German reff, Swedish ref, Norwegian riv, Danish reb likely all are from the Old Norse word.

1706, "small piece of meat," especially veal or mutton, cut horizontally from the upper part of the leg, from French côtelette, from Old French costelette "little rib" (14c.), a double diminutive of coste "rib, side," from Latin costa (see coast (n.)); influenced by unrelated English cut (n.).

"pertaining to the ribs, or the side of the body," 1630s, from French costal (16c.), from Medieval Latin costalis, from costa "a rib" (see coast (n.)).

"large variety of apple," late 14c., coster; late 13c. in Anglo-Latin, perhaps from Anglo-French or Old French coste "rib" (from Latin costa "a rib;" see coast (n.)), if the notion is "a large apple with prominent 'ribs,' " i.e. one having a shape more like a green pepper than a plain, round apple. Also applied derisively to "the head" on resemblance to an apple. The word was common 14c.-17c. but later was limited to fruit-growers.