Mark Liberman at the Log has a post about an interesting fact I was unaware of: the name of the H0/HO scale of model railway is from “half zero.” Accordingly, the Wikipedia talk page contains a vigorous prescriptivist (“The correct name is ‘H0’ or ‘half zero’; Google only shows that most people do it wrong“) versus descriptivist (“You seem to have forgotten that what was and what is are two separate situations. Your argument is the same as arguing that if a word is a Latin derivative, then it is still a Latin word and should be spelled the same”) debate. I’m sure you can guess which side I come down on.
Totally unrelated, but a comment by Christopher Squire on Pepys’ Diary explains an interesting premodern usage by quoting the OED:
pragmatical, adj. and n.
. . 3.a. Officious, meddlesome, interfering; intrusive. Obs.
. . b. Conceited, self-important, pompous; opinionated; dogmatic, unbending.
1660 H. More Explan. Myst. Godliness iv. xiii. 131 The leguleious Cavils of some Pragmatical Pettifoggers.
1668 J. Glanvill Blow at Mod. Sadducism Pref. sig. A2, With a pert and pragmatical Insolence, they censure all.
1712 J. Addison Spectator No. 481. ¶4 Lacqueys were never so saucy and pragmatical, as they are now-a-days.
1724 Swift Let. to Molesworth 2 Which‥ may perhaps give me the Title of Pragmatical and Overweening.
1779 F. Burney Let. 25 Oct.–3 Nov. in L. E. Troide & S. J. Cooke Early Jrnls. & Lett. Fanny Burney (1994) 407 His extreme pomposity,—the solemn stiffness of his Person‥& the quaint importance of his delivery,—are‥ like some Pragmatical‥ old Coxcomb represented on the stage.’
As Christopher says, “A useful word which has gone out of use for some reason tho’ the type it describes is still with us.”