1. Aggressively challenge in speech or writing
   "The critic lashed out at the author's latest work";
   - attack, round, assail, assault
    
2. [Brit, informal] Spend money extravagantly, esp. to indulge oneself
   "He lashed out on expensive electronics during the sale";
   - splurge [informal], splash out [Brit, informal], lash [Brit, informal]

Derived forms: lashing out, lashed out, lashes out

Type of: consume, criticise [Brit], criticize, damn [informal], knock [informal], pick apart, squander, ware [archaic], waste