overlash

from The Collaborative International Dictionary of English v.0.48

Overlash \O`ver*lash"\, v. i. [Cf. Prov. E. lash extravagant,
   lashing lavish.]
   To drive on rashly; to go to excess; hence, to exaggerate; to
   boast. [Obs.] --Barrow.
   [1913 Webster]