The Latin word is perpendiculum (or the adjective pendulus from which the neuter noun pendulum was later derived long after the days of Classical Latin), so "pendula" cannot be a correct original Latin form. At best it is an invented plural from the seventeenth century, pretending to be a Latin form. Dbfirs 21:36, 27 May 2009 (UTC)
- I’ve marked it as “hypercorrect”, the term of art for these latter-day formations, and expanded the etymology – how does it look?
- —Nils von Barth (nbarth) (talk) 16:33, 28 May 2009 (UTC)
- Yes, I'm happy with your improvement, and I'm surprised at how often "coupled pendula" occurs (though "coupled pendulums" is twice as common). I suppose we need to strike a balance between recording common "hypercorrect" errors (especially by physicists?) and giving the impression that all plurals are equally valid. Thanks, and sorry for the delay in replying. Dbfirs 09:00, 6 June 2009 (UTC)