the GNU version of the Collaborative International Dictionary of English
adj. Costing nothing.
The Century Dictionary and Cyclopedia
Costing nothing; not involving expense.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. costing nothing
Word Usage
"The S&L crisis of the 1980s showed that "costless" guarantees can turn into real on-budget expenditures -- more than $120 billion worth at that time."