countryside n.

mid-13c., "(one's) native land;" c. 1300, "any geographic area," sometimes with implications of political organization, from Old French contree, cuntrede "region, district, country," from Vulgar Latin *(terra) contrata "(land) lying opposite," or "(land) spread before one," in Medieval Latin "country, region," from Latin contra "opposite, against" (see contra-). The native word is land.

Also from c. 1300 as "area surrounding a walled city or town; the open country." By early 16c. the word was applied mostly to rural areas, as opposed to towns and cities. Meaning "inhabitants of a country, the people" is from c. 1300.

INTERVIEWER [Steve Rossi]: "Would you say you're the best fighter in the country?

PUNCH-DRUNK BOXER [Marty Allen]: "Yeah, but in the city they murder me." 

As an adjective from late 14c., "peculiar to one's own country (obsolete); by 1520s as "pertaining to or belonging to the rural parts of a region," typically with implications of "rude, unpolished."

Country air "fresh air" is from 1630s. First record of country-and-western as a music style is by 1942, American English. Country music is by 1968. Country club "recreational and social club, typically exclusive, located in or near the country" is by 1886. Country mile "a long way" is from 1915, American English. Country-mouse is from 1580s; the fable of the mouse cousins is as old as Aesop. Country road "road through rural regions" is from 1873.

Old English side "flanks of a person, the long part or aspect of anything," from Proto-Germanic *sīdō (source also of Old Saxon sida, Old Norse siða, "flank; side (of meat); coast," Danish side, Swedish sida, Middle Dutch side, Dutch zidje, Old High German sita, German Seite), from adjective *sithas "long" (source of Old English sid "long, broad, spacious," Old Norse siðr "long, hanging down"), from PIE root *se- "long; late" (see soiree).

The "long part of anything" sense is preserved hillside, it also was in 16c.-17c. side-coat "long coat." From 14c. as "lateral half of the body of a slaughtered animal." In reference to bacon, it indicates position relative to the ribs. The meaning "a region, district" is from c. 1400, as in South Side, countryside.

The figurative sense of "position or attitude of a person or set of persons in relation to another" (as in choose sides, side of the story) is recorded by mid-13c. As "an aspect" of anything immaterial (the bright side, etc.), by mid-15c.

The meaning "one of the parties in a transaction" is from late 14c.. The sense of "one of the parties in a sporting contest or game" is from 1690s. The meaning "music on one side of a phonograph record" is attested by 1936. As short for side-dish, by 1848.

The phrase side by side "close together and abreast, placed with sides near together" is recorded from c. 1200. Colloquial on the side "in addition," especially "unacknowledged," with connotations of "illicit, shady," is by 1893.