One of the more interesting little sub-fields in linguistics is diachronic semantics. That’s the study of how word meanings change over time. Some of these changes are relatively easy to track. A “mouse” to a farmer in 1900 was a small rodent with unfortunate grain-pilfering proclivities. To a farmer today, it’s also one of the tools she uses to interact with her computer. The word has gained a new semantic sense without losing it’s original meaning. Sometimes, however, you have a weird little dance where a couple of words are negotiating over the same semantic space–that’s another way of saying a related group of concepts that a language groups together–and that’s where things get interesting. “Cup”, “mug” and “glass” are engaged in that little dance-off right now (at least in American English). Let’s see how they’re doing, shall we?
Cup: Ok, quick question for you: does a cup have to have a handle? The Oxford dictionaries say “yes“, but I really think that’s out of date at this point. Dr. Reed pointed out that this was part of her criteria for whether something could be called a “cup” or not, but that a lot of younger speakers no longer make that distinction. In fact, recently I noticed that someone of my acquaintance uses “cup” to refer only to disposable cups. Cup also has the distinct advantage of being part of a lot of phrases: World cup, Stanley cup, cup of coffee, teacup, cuppa, cup of sugar, in your cups, and others that I can’t think of right now.
So “cup” is doing really well, and gaining semantic ground.
Glass: Glass, on the other hand, isn’t doing as well. I haven’t yet talked to someone who can use “glass” to refer to drinking vessels that aren’t actually made of glass including, perhaps a little oddly, clear disposable cups. On the other hand, there are some types of drinking vessels that I can only refer to as glasses. Mainly those for specific types of alcohol: wine glass, shot glass, martini glass, highball glass (though I’ve heard people referring to the glass itself just as a highball, so this might be on the way out). There are alcohol-specific pieces of glassware that don’t count as glasses though–e.g. champagne flute, brandy snifter–so it’s not a categorical distinction by any means.
“Glass” seems to be pretty stable, but if “cup” continues to become broader and broader it might find itself on the outs.
Mug: I don’t have as much observational data on this one, but there seems to be another shift going on here. “Mug” originally referred only to drinking vessels that were larger than cups (see below), and still had handles.
Most people call those insulated drinking vessels with the attached lids “travel mugs” rather than “travel cups” (640,000 Google hits vs. 22,400) but I find myself calling them “cups” instead. I think it’s because 1) I pattern it with disposable coffee cups and 2) I find handledness is a necessary quality for mugs. I can call all of the drinking vessels in the picture above “mugs” and prefer “mug” to “cup”.
So, at least for me, “mug” is beginning to take over the semantic space allotted to “cup” by older speakers.
Of course, this is a very cursory, impressionistic snapshot of the current state of the semantic space. Without more robust data I’m hesitant to make concrete predictions about the ways in which these terms are negotiating their semantic space, but there’s definitely some sort of drift going on.