drop 
(drŏp)
(drŏp)n.
1.
a. A small amount of a liquid, drawn into a roughly spherical mass by surface tension.
b. The quantity of liquid contained in such a mass, especially when measured out by a dropper.
c. drops Liquid medicine administered in drops.
d. A small quantity of a liquid: There isn't a drop of milk left.
e. Informal An alcoholic drink: a man known to have a drop now and then.
2. A trace or hint: not a drop of pity.
3.
a. Something, such as an earring, shaped or hanging like a drop.
b. A small globular piece of hard candy.
4. The act of falling; descent: the drop of the curtain; the sun's drop toward the horizon.
5. A swift decline or decrease, as in quality, quantity, or intensity: a drop in sales.
6.
a. The vertical distance from a higher to a lower level: The cliff has a drop of 50 feet.
b. The distance through which something falls or drops.
7. A sheer incline, such as the face of a cliff: Stay clear of the drop.
8.
a. A descent or delivery of something by parachute: made a drop of supplies to the explorers.
b. Personnel and equipment landed by means of parachute.
9. Something, such as a trapdoor on a gallows, that is arranged to fall or be lowered.
10. A drop curtain.
11. A slot through which something is deposited in a receptacle.
12. A central place or establishment where something, such as mail, is brought and subsequently distributed.
13.
a. A predetermined location for the deposit and subsequent removal of secret communications or illicit goods, such as drugs.
b. The act of depositing such communications or materials.
14. Electronics A connection made available for an input or output unit on a transmission line.
v. dropped, drop·ping, drops
v.intr.
1. To fall in drops: rain dropping from an umbrella.
2. To fall from a higher to a lower place or position: The plate dropped onto the floor.
3. To become less, as in number, intensity, or volume: The temperature dropped below 0.
4. To move or descend from one height or level to another: He dropped into a crouch. The sun dropped below the horizon.
5. To fall or sink into a state of exhaustion or death.
6. To pass or slip into a specified state or condition: dropped into a doze; drop out of sight.
7. Sports To fall or roll into a basket or hole. Used of a ball.
v.tr.
Phrasal Verbs: 1. To let fall by releasing hold of: I dropped the towel onto the floor.
2. To let fall in drops: drop the medicine into the ear.
3. To cause to become less; reduce: drop the rate of production.
4. To cause to fall, as by hitting or shooting: dropped him with a left hook.
5. Sports To hurl or strike (a ball) into a basket or hole.
6. To give birth to. Used of animals.
7. To say or offer casually: drop a hint; drop a name.
8. To write at one's leisure: drop me a note.
9. To cease consideration or treatment of: dropped the matter altogether.
10. To terminate an association or a relationship with: an actor who was dropped by the talent agency.
11. To leave unfinished: drop everything and help.
12. To leave out (a letter, for example) in speaking or writing.
13. To leave or set down at a particular place; unload: I dropped the book in your office.
14. Informal To spend, especially lavishly or rashly: "dropping $50,000 in an Atlantic City casino" (George F. Will).
15. To airdrop (supplies, for example).
16. To lower the level of (the voice).
17. To lose (a game or contest, for example).
18. Slang To take, as a drug, by mouth: drop acid.
drop back
Football To back away from the line of scrimmage.
drop behind
To fall behind: dropped behind the rest of the class during her illness.
drop by
To stop in for a short visit.
drop off
1. To fall asleep.
2. To decrease: Sales dropped off in the fourth quarter.
drop out
1. To withdraw from participation, as in a game, club, or school.
2. To withdraw from established society, especially because of disillusion with conventional values.
drop over
Idioms: To stop in for a short visit.
at the drop of a hat
1. Immediately; without delay: would sign the contract at the drop of a hat.
2. With only the slightest provocation: ready to argue at the drop of a hat.
drop a dime Slang
To make a telephone call, especially to the police to inform on or betray someone.
drop in the bucket
A small, inadequate quantity.
drop the ball
To make a mistake or fail to do something important.
get/have the drop on
To achieve a distinct advantage over.
[Middle English droppe, from Old English dropa; see dhreu- in the Appendix of Indo-European roots.]