exchange

noun

• An act of exchanging or trading.

  "All in all, it was an even exchange."

• A place for conducting trading.

  "The stock exchange is open for trading."

• A telephone exchange.
• The fourth through sixth digits of a ten-digit phone number (the first three before the introduction of area codes).

  "NPA-NXX-1234 is standard format, where NPA is the area code and NXX is the exchange."

• A conversation.

  "After an exchange with the manager, we were no wiser."

• The loss of one piece and associated capture of another
• The thing given or received in return; especially, a publication exchanged for another.
• The transfer of substances or elements like gas, amino-acids, ions etc. sometimes through a surface like a membrane.
• The difference between the values of money in different places.