(1) Not functioning (temporarily or permanently)
"We can't work because the computer is down"
"The shades were down"
(3) Understood perfectly
"Had his algebra problems down"
(4) Being or moving lower in position or less in some value
"Lay face down"
"The moon is down"
"Our team is down by a run"
"Down by a pawn"
"The stock market is down today"
(5) Spatially or metaphorically from a higher to a lower level or position
"Don't fall down"
"Rode the lift up and skied down"
"Prices plunged downward"
(6) Away from a more central or a more northerly place
"Was sent down to work at the regional office"
"Worked down on the farm"
"Came down for the wedding"
"Flew down to Florida"
(7) Paid in cash at time of purchase
"Put ten dollars down on the necklace"
(8) In an inactive or inoperative state
"The factory went down during the strike"
"The computer went down again"
(9) To a lower intensity
"He slowly phased down the light until the stage was completely black"
(10) From an earlier time
"The story was passed down from father to son"
(11) (American football) a complete play to advance the football
"You have four downs to gain ten yards"
(12) Soft fine feathers
(13) Fine soft dense hair (as the fine short hair of cattle or deer or the wool of sheep or the undercoat of certain dogs)
(14) (usually plural) a rolling treeless highland with little soil
(15) English physician who first described Down's syndrome (1828-1896)
(16) Improve or perfect by pruning or polishing
"Refine one's style of writing"
(17) Bring down or defeat (an opponent)
(18) Eat immoderately
"Some people can down a pound of meat in the course of one meal"
(19) Drink down entirely
"He downed three martinis before dinner"
"She killed a bottle of brandy that night"
"They popped a few beer after work"
(20) Cause to come or go down
"The policeman downed the heavily armed suspect"
"The mugger knocked down the old lady after she refused to hand over her wallet"
(21) Shoot at and force to come down
"The enemy landed several of our aircraft"