B2 a measured amount of something such as medicine:
a high/low dose
a dose of penicillin
The label says to take one dose three times a day.
20 or 30 of these pills would be a lethal dose (= enough to kill you).
B2 an amount or experience of something, often something bad or unpleasant:
The government received a hefty dose of bad news this week.
UK She's got a nasty dose of flu.
UK slang a case of gonorrhoea (= a disease of the sexual organs)