abonar
pay
bonus
extra payment
+
-ar
verb suffix
Abonar means to pay and can be thought of as bonus0 + -ar1 (verb1), like giving a bonus payment.
verb
  1. pay
    To pay, to credit, or to deposit money
    Necesito abonar dinero en mi cuenta. // I need to deposit money into my account.
  2. fertilize
    To fertilize or enrich soil
    Es importante abonar la tierra antes de plantar. // It's important to fertilize the soil before planting.