the act of distributing by allotting or apportioning; distribution according to a plan; "the apportionment of seats in the House of Representatives is based on the relative population of each state"
(chemistry) a process in which one substance permeates another; a fluid permeates or is dissolved by a liquid or solid
(physics) the process in which incident radiated energy is retained without reflection or transmission on passing through a medium; "the absorption of photons by atoms or molecules"