verb

• (transitive) To collect and remove refuse, or to search through refuse, carrion, or abandoned items for useful material.
• (transitive) To remove unwanted material from something, especially to purify molten metal by removing impurities.
• (transitive) To expel the exhaust gases from the cylinder of an internal combustion engine, and draw in air for the next cycle.
• (intransitive) To feed on carrion or refuse.