In a lower position or place than: a rug under a chair. To or into a lower position or place than: rolled the ball under the couch. Beneath the surface of: under the ground; swam under water. Beneath the assumed surface or guise of: traveled under a false name. Less than; smaller than: The jar's capacity is under three quarts. Less than the required amount or degree of: under voting age. Inferior to in status or rank: nine officers under me at headquarters. Subject to the authority, rule, or control of: under a dictatorship. Subject to the supervision, instruction, or influence of: under parental guidance. Undergoing or receiving the effects of: under constant care. Subject to the restraint or obligation of: under contract. Within the group or classification of: listed under biology. In the process of: under discussion. In view of; because of: under these conditions. With the authorization of: under the monarch's seal. Sowed or planted with: an acre under oats. Nautical Powered or propelled by: under sail; under steam. During the time conventionally assigned to (a sign of the zodiac): born under Aries. In or into a place below or beneath: struggled in the water but then slipped under. In or into a subordinate or inferior condition or position. So as to be covered or enveloped. So as to be less than the required amount or degree. Located or situated on a lower level or beneath something else: the under parts of a machine. Lower in rank, power, or authority; subordinate. Less than is required or customary: an under dose of medication.