Atlantic has 5 different meanings across 3 categories:
Noun · Adjective · Proper Noun
the 2nd largest ocean; separates North and South America on the west from Europe and Africa on the east
"The cruise ship crossed the Atlantic to sail from New York City to London."
A steam locomotive of the 4-4-2 wheel arrangement.
"The Great Northern Railway operated several Atlantic class steam locomotives to haul heavy freight trains across the northern states."
In plain English: An Atlantic is not actually a noun; it refers to either the huge ocean between North and South America on one side, Europe and Africa on the other, or anything related to that specific body of water.
"The sailors stayed aboard until they crossed the Atlantic Ocean to reach their destination in America."
Pertaining to the Atlantic Ocean.
"The ship sailed across the atlantic waters toward its destination."
In plain English: Atlantic describes anything related to the huge ocean between North and South America on the west side and Europe and Africa on the east side.
"The cruise ship crossed the Atlantic Ocean to reach its destination in Europe."
The Atlantic Ocean.
"The cruise ship sailed across the Atlantic toward Europe."
From Middle English Atlantyke, from Latin Ā̆tlanticus, from Ancient Greek Ἀτλαντικός (Atlantikós, "Atlantean, of Atlas"), from Ancient Greek Ἄτλᾱς (Átlās), either from ἁ- (ha-, copulative prefix) + Proto-Indo-European *telh₂- ("bear, undergo, endure") or of Pre-Greek origin.