Noun dosage has 2 senses

• dosage(n = noun.quantity) dose - the quantity of an active agent (substance or radiation) taken in or absorbed at any one time; Array
is a kind of indefinite quantity
Derived forms verb dose₂, verb dose₁

• dosage(n = noun.artifact) dose - a measured portion of medicine taken at any one time; Array
has particulars: booster, booster dose, booster shot, recall dose, draft, draught, hit, lethal dose, lozenge, pill, tab, tablet
is a kind of medicament, medication, medicinal drug, medicine