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.
‘That’ll do very well,’ said Alice: and “slithy”?’
‘Well, “slithy” means “lithe and slimy.” “Lithe” is the same as “active.” You see it’s like a portmanteau—there are two meanings packed up into one word.’
Alice’s adventures in Wonderland, of course, proved very popular, and while ‘slithy’ may not have made it into the dictionary, the portmanteau idea was so clever that it has stuck ever since. Longer, in fact, than the big leather suitcases it once described and the dapper hats that went with them.