What economic term describes benefiting from a public good without contributing to its cost?

Free rider problem

The free rider problem occurs with 'public goods,' which are services like street lighting or national defense that people cannot be easily excluded from using. Because individuals can enjoy these benefits without paying, it often leads to a market failure where the good is under-provided or not provided at all. A classic example is a lighthouse, which provides safety to all passing ships regardless of whether they contributed to its upkeep.