Atlantic (adj.)

1580s, in Greek mythology a member of the older family of Gods, later regarded as a Titan, son of Iapetus and Clymene; in either case supposed to uphold the pillars of heaven (or earth), which according to one version was his punishment for being war-leader of the Titans in their battle with the Olympian gods. "Originally the name of an Arcadian mountain god; the name was transferred to the mountain chain in Western Africa" [Beekes].

The Greek name traditionally is interpreted as "The Bearer (of the Heavens)," from a-, copulative prefix (see a- (3)), + stem of tlenai "to bear" (from PIE root *tele- "to lift, support, weigh"). But Beekes compares Berber adrar "mountain" and finds it plausible that the Greek name is a "folk-etymological reshaping" of this. Mount Atlas, in Mauritania, was important in Greek cosmology as a support of the heavens.

by 1804, "the middle of the Atlantic Ocean," from mid (adj.) + Atlantic. In U.S. history, Mid-Atlantic states in reference to the middle states on the Atlantic coast is by 1842.

also trans-atlantic, "on the opposite side of the Atlantic from the speaker," 1779, from trans- "through, across" + Atlantic. Compare French transatlantique.