The term 'Booster Amount' can be broken down into two crossword solutions: DOSE (4 letters) and TURBO (5 letters). DOSE is a noun that refers to the amount of a substance, such as medicine, that is taken or administered at any one time. Turbo is an adjective that describes something that has been increased in power or speed, usually by using a turbocharger. Together, these two words can be used to describe a large amount of power or speed that has been added to something.