"vast stores of gas under the North Sea"

• below (something covering or protecting)

  "under several feet of water"

"the room under his study"

• behind (a physical surface)

  "it was written on the new canvas under a gluey coating"

• behind or hidden behind (an appearance)

  "he had a deep sense of fun under his quiet exterior"

• lower in grade or rank than

  "under him in the hierarchy"

"they averaged just under 2.8 per cent"

"the province is now under martial law"

• during the rule of

  "the coinage standard was reformed under Elizabeth I"

• as a reaction to or undergoing the pressure of (something)

  "the sofa creaked under his weight"

• as provided for by the rules of; in accordance with

  "flowers supplied under contract by a local florist"

• used to express grouping or classification

  "file it under ‘lost’"

• within the environment of (a particular operating system)

  "the program runs under DOS"

"under construction"

• in a state of

  "children living under difficult circumstances"

• planted with

  "fields under wheat"

"weaving the body through the crossbars, over and under, over and under"

"he was floating for some time but suddenly went under"

• affected by an anaesthetic; unconscious

  "the operation was quick; she was only under for 15 minutes"