noun

• (formal or archaic) Substitution of one thing for another; interchange.
• Specifically, the substitution of one kind of payment for another, especially a switch to monetary payment from obligations of labour.
• (law) The change to a lesser penalty or punishment by the State
• (linguistics) Substitution, as a means of discriminating between phonemes.
• (electronics) The reversal of an electric current.
• (obsolete) A passing from one state to another; change; alteration; mutation.
• (obsolete) The act of giving one thing for another; barter; exchange.
• (US, nonstandard) The process or habit of journeying to and from work on a regular basis; commuting.