Word | Noun | Adjective | Verb | Adverb |
---|---|---|---|---|
alternative energy | Yes | No | No | No |
free energy | Yes | No | No | No |
alternative energy (noun) | free energy (noun) |
---|---|
energy derived from sources that do not use up natural resources or harm the environment | (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs |