under in WordNet English dictionary

1. further down
   "see under for further discussion"
   under  below  under  below 
   
2. down below
   "get under quickly!"
   under  under 
   
3. below the horizon
   "the sun went under"
   under  under 
   
4. below some quantity or limit
   "fifty dollars or under"
   under  under 
   
5. in or into a state of subordination or subjugation
   "we must keep our disappointment under"
   under  under 
   
6. down to defeat, death, or ruin
   "their competitors went under"
   under  under 
   
7. into unconsciousness
   "this will put the patient under"
   under  under 
   
8. through a range downward
   "children six and under will be admitted free"
   under  under 
   

1. located below or beneath something else
   "nether garments"; "the under parts of a machine"
   nether  under 
   
2. lower in rank, power, or authority
   "an under secretary"
   under