mercar
buy
mercado
market
+
-ar
verb suffix
Mercar means to buy and can be thought of as mercado0 (market0) + -ar1 (verb suffix1), literally meaning 'to market' or engage in market activities.
verb
  1. buy
    To buy or purchase goods
    Voy a mercar comida para la semana. // I'm going to buy food for the week.