| Word | Definitions | Synonyms |
|---|---|---|
| flyway | (noun) the geographic route along which birds customarily migrate | Synonyms: migration route |
| flyweight | (noun) A weight class division in combat sports, often the lightest. | - |
| (noun) an amateur boxer who weighs no more than 112 pounds | - | |
| (noun) weighs no more than 115 pounds | - | |
| flywheel | (noun) regulator consisting of a heavy wheel that stores kinetic energy and smooths the operation of a reciprocating engine | - |