Sunbelt (n.)

Old English sunne "the sun," from Proto-Germanic *sunno (source also of Old Norse, Old Saxon, Old High German sunna, Middle Dutch sonne, Dutch zon, German Sonne, Gothic sunno "the sun"), from PIE *s(u)wen-, alternative form of root *sawel- "the sun."

Old English sunne was feminine (as generally in Germanic), and the fem. pronoun was used in English until 16c.; since then masc. has prevailed. The empire on which the sun never sets (1630) originally was the Spanish, later the British. To have one's place in the sun (1680s) is from Pascal's "Pensées"; the German imperial foreign policy sense (1897) is from a speech by von Bülow.

Old English belt "belt; girdle; broad, flat strip or strap of material used to encircle the waist," from Proto-Germanic *baltjaz (source also of Old High German balz, Old Norse balti, Swedish bälte), an early Germanic borrowing from Latin balteus "girdle, sword belt," said by Varro to be an Etruscan word.

Transferred sense of "broad stripe encircling something with its ends joined" is from 1660s; that of "broad strip or tract" of any sort, without notion of encircling (as in Bible belt is by 1808). As a mark of rank or distinction, mid-14c.; references to boxing championship belts date from 1812. Mechanical sense is from 1795. Below the belt "unfair" (1889) is from pugilism. To get something under (one's) belt was originally literal, to get it into one's stomach (1839), figurative use by 1931. To tighten (one's) belt "endure privation" is from 1887.