What does "feeder" mean?

Additional senses

1. 2.One who eats or feeds; specifically, an animal to be fed or fattened. With eager feeding, food doth choke the feeder. Shak.
2. 3.One who fattens cattle for slaughter.
3. 4.A stream that flows into another body of water; a tributary; specifically (Hydraulic Engin.), a water course which supplies a canal or reservoir by gravitation or natural flow.
4. 5.A branch railroad, stage line, or the like; a side line which increases the business of the main line.
5. 6.(Mining) (a) A small lateral lode falling into the main lode or mineral vein. Ure. (b) A strong discharge of gas from a fissure; a blower. Raymond.
6. 7.(Mach.) An auxiliary part of a machine which supplies or leads along the material operated upon.
7. 8.(Steam Engine) A device for supplying steam boilers with water as needed.