How did pedestrian come to mean both (1) a person travelling on foot, and (2) dull, ordinary, uninspired?

Well, without looking at any sources, I'd say it's because pedestrians are slower-moving than those in cars (or more likely, those on horseback or in carriages, considering the presumed age of the expression).

The "slow-moving" or "plodding" meaning then moved towards the meaning you give.

From reading the online OED, it sounds like there is some difference in the etymology. The "on foot" etymology comes from the Latin "pedestr-, pedester, also pedestris (see PEDESTRIAL a.) + -AN; cf. -IAN. With sense A. 2a cf. French pédestre (of a statue) on foot, not equestrian (1721). Cf. earlier PEDESTRIAL a. and EQUESTRIAN a.

The "commonplace" definition, however, also comes from ancient Greek: "With sense A. 1 perh. cf. also ancient Greek (Greek letters that wouldn't copy) in prose, prosaic, plain, commonplace, uninspired (sometimes contrasted with the winged flight of Pegasus)." Sorry that I couldn't copy those Greek letters. But it does sound as though there is a different etymology for both.

Pedestrian, in the sense of commonplace, is also from the Latin pedester. What the entry you quote says does is to compare the Greek word pezos which means literally 'on foot' in Greek with Latin pedester, but also has an extended meaning 'common, ordinary'. Both the Latin and Greek words are related to the PIE root for foot: Latin pes, pedis, and Greek pous, podos.

Oh, thanks, Zmj. In other words, Arnie was right after all. What else is new?

I just have the worst time understanding the etymology in the OED. Sorry to have confused, folks.

quote:

cf. also ancient Greek (Greek letters that wouldn't copy)

πεζός

It may well turn out to be as arnie and zmj say, but reaching the conclusion is not as simple as that.The question is why 'pedestrian' has two such different meanings, one pertaining to feet and the other to dullness. Or (since the 'foot' meaning is obvious for the -ped- root), we could just ask how the non-feet meaning evolved.

If (as zmj says) the Latin predecessor word had the same two meanings, that doesn't really answer the question. It just shifts it from "How did the English word get the non-feet meaning?" to "How did the Latin word get it?"

However, can any of our scholars confirm whether the Latin word actually did have any 'non-feet' sense? I have my doubts. On the one had OED says so. On the other hand, it says so only in a couple of words in passing; it there OED implies two non-feet senses to be explained; and neither of those two supposed non-feet senses led to any other english word. So did the Latin term truly have those non-feet senses? Or is that claim just a deus ex machina trotted out to resolve the etymological question posed atop this thread?

If we can't confirm that that Latin word did have non-feet meanings, then I'd make the SWAG. that the non-feet sense of 'pedestrian' came from -paed- or -ped-, meaning 'boy', as in pedophile, pediatrics, etc.

PS: SWAG = Stupid Wild-Ass Guess