druid: [16] Druid is, not surprisingly, of Celtic origin, although English probably acquired it via French druide or the Latin plural druides. The source of these forms was Gaulish druides, which came ultimately from Old Celtic *derwíjes. There are two opposing theories on the derivation of this: one is that it comes from an Old Celtic adjective derwos ‘true’ (source of Welsh derw ‘true’), in which case its etymological meaning would be ‘someone who says the truth’ (a parallel formation to English soothsayer); the other is that it was formed from the Old Celtic base *dru- ‘tree’ (source of Welsh derwen and Irish daur ‘oak-tree’ and related to Greek drus ‘oak’ and English tree) in reference to the central role played by oak-trees in druidic ceremonies.
