Etymology Dictionary

WARBLE,  to sing as a bird, chirp, carol.  (F.,—M.H.G.)   M.E. werblen, spelt werbelen, Gawain and the Grene Knight, 2004; the sb. werble occurs in the same, 119.—O.F. werbler, to quaver with the voice, speak in a high tone (Burguy, Roquefort).—M.H.G. werbelen*, not given in Wackernagel, yet merely the old spelling of mod. G. wirbeln, to whirl, to run round, to warble, frequentative form of M.H.G. werben, O.H.G. hwerban, to be busy, to set in movement, urge on (whence mod. G. be-werben, to sue for, er-werben, to acquire), the orig. sense being to twirl oneself about, to twirl or whirl.   See Whirl, which is, practically, a doublet.   Der. warble, sb., M.E. werble, as above; warbl-er.