Portmanteau, combining two words and two meanings
Originally the word portmanteau didn’t mean anything at all. ‘Port’ is a French prefix denoting an object that carries the word following it. ‘Manteau’ means cloak. With the two together, you now have the word for a cloak-carrying object. That’s right, a suitcase.
In its earliest incarnations, portmanteau referred to any bag that could easily be carried on horseback, but it evolved over time to mean the big, hinged, hard-sided pieces we would normally imagine today. Think one of those hefty leather jobs that look really good on old steam trains, preferably surrounded by dapper gents in suave hats and ladies with plenty of silk.