allotment
A specific share or portion of something given to someone.
An allotment is a specific portion of something that has been distributed or assigned to someone. When a teacher divides the class into groups for a project and gives each group an allotment of art supplies, she's making sure everyone gets their fair share of markers, paper, and glue. When a family goes camping and each person receives their allotment of trail mix for the hike, everyone knows exactly how much they can eat before reaching the summit.
During World War II, the government gave families allotments of sugar, butter, and gasoline because these items were scarce. Each family received coupons that allowed them to buy only their assigned portion, ensuring everyone got some rather than a few people taking it all.
You might also hear about a time allotment for a presentation, meaning you have a specific number of minutes to speak. If your allotment is five minutes, that's your share of the available time. You can't take more without being unfair to the next speaker. The word emphasizes both the idea of receiving your portion and the responsibility to stay within it.