What is Under ?
Under is prep 1. in or to a place where something else is on top or above We all hid under the table. My pen rolled under the sofa. 2. less than a number No one wanted the old table – it was sold for un- der £10. It took under two weeks to sell the house. The train goes to Paris in under three hours. Under half of the members turned up for the meeting. 3. younger than She’s a managing director and she’s still un- der thirty. 4. according to Under the terms of the agreement, the goods should be deliv- ered in October. 5. controlled by a ruler The country enjoyed a period of peace under the rule of the British governors. adv in a lower place to go under to fail, to go bank- rupt The company went under during the recession.
source: Easier English, Student Dictionary Upper Intermediate Level