costless
1. [ adjective ] costing nothing
Synonyms: free gratuitous gratis complimentary
Examples:

"complimentary tickets"

Related terms: unpaid
Similar spelling:   costliness
  Costales
  Costley
  coastline
  costly
  costal
  coastal
  Costilow
  Costillo
  Costilla
  Costello
  Costella