Meaning:
2-hydroxybenzoic acid 
n.
a white crystalline substance with a bitter aftertaste; used as a fungicide or in making aspirin or dyes or perfumes
dro Idiom, Proverb
a drop in the bucket
a small part, a tiny piece, the tip of the iceberg This donation is only a drop in the bucket, but it is appreciated.
at the drop of a hat
without waiting, immediately, promptly He will stop working and help you at the drop of a hat if you ask him politely.
bottom fall out/drop out
to fall below an earlier lowest price When the bottom fell out of the coffee market many companies had to stop doing business.
drop
stop taking a subject, withdraw, drop out You wouldn't drop English! It's the key to other subjects.
drop a bundle
lose money by gambling, lose your shirt I dropped a bundle at the track last night. I lost every bet.
drop a hint
suggest, give a sign When he was hungry, he'd drop a hint, like point at the fridge.
drop a line
write a letter, send a postcard Be sure to drop us a line from Paris. Tell us about your trip.
drop a log
have a bowel movement, take a shit What a smell! Open a window after you drop a log, eh.
drop a name/drop names
pretend you know famous people, name dropper He was dropping names at the interview - Klein, Clinton etc.
drop back
move or step backwards, retreat During the hike his foot began to get sore so he decided to drop back and rest for awhile.
drop behind
run further behind, lose ground Our party has dropped behind in the polls. We're in second place.
drop by
to visit someone or somewhere He dropped by after work for a drink.
drop by the wayside
give up or fail before the finish Many runners dropped by the wayside as the marathon continued.
drop charges
withdraw complaints, not press charges I realized it was an accident, so I dropped the charges.
Drop dead!
go away and be quiet, stop bothering someone I told him to drop dead when he came into my room and now he is angry at me.
drop dead
you are badly mistaken, go to hell If you think I'm getting on that motorcycle, you can drop dead.
drop her/him
leave her, not date her anymore, tube her (see tube him) She wouldn't quit smoking, so I dropped her - told her it was off.
drop him like a hot potato
leave him, not associate with him If she finds out you're not rich, she'll drop you like a hot potato.
drop-in
visitor, one who drops in He was a drop-in at the Seniors' Centre. He liked to go there.
drop in the bucket
(See a drop in the bucket)
drop it
stop talking about it, do not say any more When I mentioned his accident, he told me to drop it.
drop like flies
dying in great numbers, falling dead on the floor When a pox infected the tribe, people were dropping like flies.
drop off
go to sleep, doze, fall asleep I only dropped off for a second. I was awake for the news.
drop out
quit, stop attending I have decided not to drop out of school. I'm going to continue.
drop out (of school)
quit school or a course of some kind She dropped out of the class after three months.
drop out of sight
disappear, not be seen for awhile After the scandal, he dropped out of sight. I haven't seen him.
drop over
visit, come and talk Our friends dropped over last night for a cup of coffee.
drop (someone) a line
write or mail a note or letter to someone She promised that she would drop me a line when she gets to Singapore.
drop someone a line
write to someone.
drop your drawers
take your pants down, remove your shorts Don't you hate it when you have to drop your drawers for a nurse?
drop your gloves (hockey)
remove your gloves to fight with your fists Don't drop your gloves in this game. There's no fighting.
drown one
drink alcohol to forget one
drown out
make so much noise that it is impossible to hear The team captain was drowned out by the cheering fans.
drown your sorrow
drink until the sadness goes away Jay drowned her sorrow in wine. Then she had a headache.
get the drop on
be quicker to start, get the jump on Stu's very quick. In faceoffs, he gets the drop on his opponents.
if you're born to hang, you won't drown
"fate controls how we die; we do not control the time and cause of our death" "After rescuing the swimmer, he said to me, ""If you're born to hang, you won't drown."""
name dropper
one who implies famous people are his friends What a name dropper! He spoke of Gordon Lightfoot as his friend.
pre-menstrual syndrome
emotional crises the week before menstruation, pms Judy says pms causes most of her personal problems.
so quiet you can hear a pin drop
very quiet, very still "The teacher said, ""Class, try to be so quiet you can hear a pin drop."""
touch a drop
drink a drop of liquor, have a drink of liquor Steve was a heavy drinker, but he hasn't touched a drop in years.
wait for the other shoe to drop
wait for the final step, wait for the conclusion, leave me hanging He said he'd make two changes. First, he resigned. I'm waiting for the other shoe to drop.
brewers droop
an inability to achieve or maintain a penile erection due to excessive consumption of alcohol
drop a clanger
to make an obvious mistake
drop a dime
to inform on someone to legal authorities; i.e., to rat someone out to the police:"Tom is a punk, because he dropped a dime on Jerry about those tags"
drop anchor
to defecate:"Where's the can? I gotta drop anchor"
drop science
to demonstrate wisdom or skill
drop teas
to have sex; usually said when a guy is talking to (or about) a girl:"Hey John, drop teas with her!!!"
drop the flag
to quit the gang
drop the kids off at the pool
to defecate:"Yo slice, I gotta drop the kids off at the pool. I'll be back in a minute"
hydro
hydroponic marijuana, which is due to an agricultural technique of cultivation in the production of cannabis, a more potent product:"Hydro, me just can't let me, high go " - Bone Thugs 'n Harmony (Buddah lovas [1995])