prep.
Function: preposition
Date: before 12th century
1 : below or beneath so as to be overhung, surmounted, covered, protected, or concealed by < under sunny skies> <a soft heart under a stern exterior> < under cover of darkness>
2 a : subject to the authority, control, guidance, or instruction of <served under the general> < under the terms of the contract> <a program that runs under any operating system> b : receiving or undergoing the action or effect of < under pressure> <courage under fire> < under the influence of alcohol> <the image of a point under a mapping> < under oath>
3 a : within the group or designation of < under this heading> b : having as name or title <traveling under an alias>
4 : less or lower than (as in size, amount, or rank) especially : falling short of a standard or required degree < under the legal age> < under par>