Either Scientific American or I don’t understand the word “theory”

Scientific American has an article about 7 Misused Science Words. Number 2 is “theory”:

Part of the problem is that the word “theory” means something very different in lay language than it does in science: A scientific theory is an explanation of some aspect of the natural world that has been substantiated through repeated experiments or testing. But to the average Jane or Joe, a theory is just an idea that lives in someone’s head, rather than an explanation rooted in experiment and testing.

Although of course I applaud the broader point they’re making — saying something is “just a theory,” as, e.g., anti-evolution types do, isn’t an argument against its validity — this doesn’t sound right to me. A theory may have been experimentally substantiated, but it need not have been.

Is string theory (which is notoriously untested by experiment) not a theory? Was general relativity not a theory during the several decades during which it had minimal experimental support?

The article supports this definition with a link to a post at something called Livescience, which says (in its entirety)

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. If enough evidence accumulates to support a hypothesis, it moves to the next step—known as a theory—in the scientific method and becomes accepted as a valid explanation of a phenomenon.

In my experience, this is not how scientists use the word. I know lots of physicists who come up with theories willy-nilly, and don’t feel the need to wait for experimental evidence before labeling them “theories.”

In the unlikely event that any creationists read this, let me reiterate: I am not saying that a theory necessarily lacks experimental support, so saying something is “just a theory” doesn’t constitute a logical argument against it. In particular, Darwinian evolution is a theory, which happens to be buttressed by phenomenal amounts of evidence.

Granted, this is pretty much just a quibble. I’m just easily irritated by cartoon descriptions of “the scientific method,” formed without paying much attention to what scientists actually do and then glibly repeated by scientists.