Real Dictionary

dose
a number of persons or things considered as a collective unit [...]
a quantity or amount considered in relation to or measured against another quantity or amount [...]
a specific quantity of a therapeutic drug or agent taken at any one time or at specified intervals [...]
the act of responding; reply or reaction [...]
countable noun: A dose of medicine or a drug is a measured amount of it which is intended to be taken at one time.
countable noun: You can refer to an amount of something as a dose of that thing, especially when you want to emphasize that there is a great deal of it.
verb: If you dose a person or animal with medicine, you give them an amount of it.