A staircase leading from a deck to the cabins or area below.
A stairway leading from one deck of a ship to another.
Origin of companionway
- From companion framed windows above a hatchway, companionway probably alteration of obsolete Dutch kompanje from Old French compagne steward's cabin, storeroom from Old Italian (camera della) compagna (cabin for) provisions, pantry from Vulgar Latin compānia things eaten with bread Latin com- com- Latin pānis bread companion1
From American Heritage Dictionary of the English Language, 5th Edition