Why do we say "fast asleep"?
Dear Straight Dope:
Where did we come up with the expression "fast asleep"? It doesn't seem to make too much sense.
Maybe not now, Mike, but "fast" as a descriptive word initially (as early as the 9th century) meant "steady" or "in place." We still see this in today's vernacular in the word "steadfast," and in bleach or fabrics described as "colorfast," meaning colors stay in place, as well as the most common use, "fast asleep." Soon, the word came to apply to vigor of emotion, and "standing fast" implied not only solidity in one position, but strong and quick defense of it. Also, the word came to mean proximity, and then immediacy, such as Chaucer's "Whan he cometh, as fast schul ye see A wonder thing, which ye saugh never er this." From the meaning of "something that will be here soon," it's pretty easy to see where the connotation of speed came about.
Now, if I haven't been too fast and loose with my research, then hopefully we've nailed the origin of this phrase down fast. Now, of course, is when the responses to the column will come at me, fast and furious. However, if you're not into etymology, you're probably fast asleep from reading this, or you fast will be.