Atlantic usually refers to the Atlantic Ocean, or to the regions and countries that border it.
It comes from Latin *Atlanticus*, from Greek *Atlantikos*, 'of Atlas', referring to the mythic giant Atlas who was said to hold up the sky near the western ocean. The ocean was named the 'Sea of Atlas', and the adjective followed.
The Atlantic carries a mythic name but very real history: it linked Europe, Africa, and the Americas in trade, migration, and sadly, slavery. When you see 'Atlantic world' in history, think of a giant, churning connector of people and ideas.
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