means A fixed allotment of something scarce—food, fuel, supplies—portioned out to each person so a limited supply can be shared rather than hoarded.

from From Latin 'ratio,' meaning reckoning, calculation, or reason—the same root that gives us 'rational' and 'ratio.' The thread is arithmetic: a ration is a reasoned portion, your share worked out by careful counting. It entered English through French 'ration' and gained its military and wartime flavor as armies and besieged cities did the grim math of feeding people on too little. So at its heart, a ration is reason applied to hunger—scarcity, divided by sums.