un·der 
(ŭndər)
(ŭndər)prep.
1.
a. In a lower position or place than: a rug under a chair.
b. To or into a lower position or place than: rolled the ball under the couch.
2. Beneath the surface of: under the ground; swam under water.
3. Beneath the assumed surface or guise of: traveled under a false name.
4. Less than; smaller than: The jar's capacity is under three quarts.
5. Less than the required amount or degree of: under voting age.
6. Inferior to in status or rank: nine officers under me at headquarters.
7. Subject to the authority, rule, or control of: under a dictatorship.
8. Subject to the supervision, instruction, or influence of: under parental guidance.
9. Undergoing or receiving the effects of: under constant care.
10. Subject to the restraint or obligation of: under contract.
11. Within the group or classification of: listed under biology.
12. In the process of: under discussion.
13. In view of; because of: under these conditions.
14. With the authorization of: under the monarch's seal.
15. Sowed or planted with: an acre under oats.
16. Nautical Powered or propelled by: under sail; under steam.
17. During the time conventionally assigned to (a sign of the zodiac): born under Aries.
adv.
1. In or into a place below or beneath: struggled in the water but then slipped under.
2. So as to be covered or enveloped: arranged the blankets so the kids were completely under.
3. So as to be less than the required amount or degree: 10 degrees or under.
4. So as to be rendered unconscious, as by an anesthetic: Doctors put the patient under.
5. In or into a condition of ruin or death: businesses that have gone under.
adj.
Idiom: 1. Located or situated on a lower level or beneath something else: the under parts of a machine.
2. Lower in rank, power, or authority; subordinate.
3. Less than is required or customary: an under dose of medication.
out from under Informal
Having gotten free of worries or difficulties: Credit counseling helped us get out from under.
[Middle English, from Old English; see dher- in the Appendix of Indo-European roots.]