suburbia n.

early 14c., "area outside a town or city," whether agricultural or residential but most frequently residential, from Old French suburbe "suburb of a town," from Latin suburbium "an outlying part of a city" (especially Rome), from sub "below, near" (see sub-) + urbs (genitive urbis) "city" (see urban). Glossed in Old English as underburg. Just beyond the reach of municipal jurisdiction, suburbs had a bad reputation in 17c. England, especially those of London, and suburban had a sense of "inferior, debased, licentious" (as in suburban sinner, slang for "loose woman, prostitute"). By 1817, the tinge had shifted to "of inferior manners and narrow views." Compare also French equivalent faubourg.

[T]he growth of the metropolis throws vast numbers of people into distant dormitories where ... life is carried on without the discipline of rural occupations and without the cultural resources that the Central District of the city still retains. [Lewis Mumford, 1922]

word-forming element in names of countries, diseases, and flowers, from Latin and Greek -ia, noun ending, in Greek especially used in forming abstract nouns (typically of feminine gender); see -a (1). The classical suffix in its usual evolution (via French -ie) comes to Modern English as -y (as in familia/family, also -logy, -graphy). Compare -cy.

In paraphernalia, Mammalia, regalia, etc. it represents Latin or Greek -a (see -a (2)), plural suffix of nouns in -ium (Latin) or -ion (Greek), with formative or euphonic -i-.