Frequency: The word is one of the 1500 most common words in English.
1.
You use ~ to express rates and ratios. For example, if something costs ?50 ~ year, you must pay ?50 each year for it. If a vehicle is travelling at 40 miles ~ hour, it travels 40 miles each hour.
Social Security refused to pay her more than ?17 ~ week...
Buses and trains use much less fuel ~ ~son than cars.
~ head: see head
PREP: amount PREP n
2.
If something happens as ~ a particular plan or suggestion, it happens in the way planned or suggested. (FORMAL)
When they reach here they complain that they are not being paid as ~ the agreement...
PREP-PHRASE