BFif a price, amount etc goes through the floor, it becomes very low [≠ go through the roof]:
Share prices have gone through the floor.
US/UK DIFFERENCE US/UK DIFFERENCE The bottom area of a building, on the same level as the land around it, is called the ground floor. In American English this can also be called the first floor. In British English the first floor is one level up from the ground. In American English this is the second floor.floor or storey/story? See note at STOREYGRAMMAR!! Say on the first/second/fifth etc floor• The cafeteria is on (NOT at/in) the top floor.WORD CHOICE: WORD CHOICE: storey, story, floorStorey (BrE) or story (AmE) is usually used to talk about the structure of a building • a building dozens of storeys high • a three-storey houseThe plural of story is stories• The office block was 20 stories high.To talk about where someone or something is in a building, use floor• We went up to the top floor. • He works on the fifteenth floor. • Is there a bathroom on this floor? ➔ See alsostoreyWORD CHOICE: WORD CHOICE: ground, land, earth, soil, floorThe ground is the surface that you walk on when you are outdoors• There were a few flakes of snow on the ground. • an area of muddy groundlandis an area of ground that is owned or controlled by someone• They were on his land. • land set aside for housingIt is also the part of the earth's surface that is not covered in water• animals that live on landearth or soilis the soft substance that covers the ground and that plants grow in• Green shoots peeped through the earth. • fertile soilThe Earth or earth is also the planet that we live on.The flooris the surface that you walk on when you are indoors• There's mud all over the floor! ➔ See alsoground
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.