the.com/steamer trunk

means A large, sturdy box-shaped travel case with a domed or flat reinforced top, designed to be packed with everything you own and checked into the hold of a ship.

from The name comes straight from its job: these trunks were built for travel aboard steamships, the engine-driven vessels that replaced sail in the 1800s. Their flat tops (unlike the humped trunks of earlier stagecoach days) let them stack efficiently in a ship's cargo hold or cabin, and their iron-banded corners and reinforced edges were made to survive being hauled, stacked, and shipped across an ocean rather than just tossed on a coach roof. The word 'steamer' itself is simply 'steamship' shortened — so a steamer trunk is, plainly, the trunk you brought on the steamer.