Definitions of absorption:

• noun:   (chemistry) a process in which one substance permeates another; a fluid permeates or is dissolved by a liquid or solid
• noun:   (physics) the process in which incident radiated energy is retained without reflection or transmission on passing through a medium

  Example: "The absorption of photons by atoms or molecules"

• noun:   the process of absorbing nutrients into the body after digestion
• noun:   the social process of absorbing one cultural group into harmony with another
• noun:   the mental state of being preoccupied by something
• noun:   complete attention; intense mental effort