Exhaust the available resources of something or someone, impoverish. Also collect the profit on a farm, collect its fruits. There are doubts about the origin of this word, but the RAE assumes it from the Latin ex- ("out, taken out") and cyma, atis ("shoot of a plant").
It means harvesting, take advantage, collect, exploit, exploit, exhausting, razing. In figurative way Rob, squeeze, swindle, bleed.