"light, crisp bits of hard bread or biscuit" ("formerly much used on board ships" - OED), 1590s, from Spanish or Portuguese rosca "roll, twist of bread," literally "coil, anything round and spiral," a word of unknown origin, perhaps from a pre-Latin Iberian language.
"a continuous emission of soft, rapid sounds; the noise made in rustling," 1759, from rustle (v.).
1620s, "action of retiring to or living in the country," from Latin rusticationem (nominative rusticatio) "act or fact of living in the country," noun of action from past-participle stem of rusticari "live or stay in the country," from rusticus (see rustic).
early 15c., of persons, "living in the countryside," from Old French rural (14c.), from Latin ruralis "of the countryside," from rus (genitive ruris) "open land, country" (from PIE *reue- (1) "to open; space;" see room (n.)).
In early examples there is usually little or no difference between the meanings of rural and rustic, but in later use the tendency is to employ rural when the idea of locality (country scenes, etc.) is prominent, and rustic when there is a suggestion of the more primitive qualities or manners naturally attaching to country life. [OED]
By 1510s as "characteristic of country life generally, rustic. Extended senses in 15c. included "lowly, unlearned, uncouth, unpretentious, unpolished;" the overal sense of "characteristic of the country, as opposed to the town," is by 1580s.
As a noun, "a country person, a peasant" mid-15c. Related: Rurally; ruralism; rurality. Wordsworth uses ruralize "give a rural character to," but ruralization was used from 1859, of persons, in the sense of "a going into the country."
Middle English roum, from Old English rum "space, extent; sufficient space, fit occasion (to do something)," from Proto-Germanic *ruman (source also of Old Norse, Old Saxon, Old High German, Gothic rum, German Raum "space," Dutch ruim "hold of a ship, nave"), nouns formed from Germanic adjective *ruma- "roomy, spacious," from PIE root *reue- (1) "to open; space" (source also of Avestan ravah- "space," Latin rus "open country," Old Irish roi, roe "plain field," Old Church Slavonic ravinu "level," Russian ravnina "a plain").
Old English also had a frequent adjective rum "roomy, wide, long, spacious," also an adverb, rumlice "bigly, corpulently" (Middle English roumli).
The meaning "chamber, cabin" is recorded by early 14c. as a nautical term; applied by mid-15c. to interior division of a building separated by walls or partitions; the Old English word for this was cofa, ancestor of cove. The sense of "persons assembled in a room" is by 1712.
Make room "open a passage, make way" is from mid-15c. Room-service is attested from 1913; room-temperature, comfortable for the occupants of a room, is so called from 1879. Roomth "sufficient space" (1530s, with -th (2)) now is obsolete.