Register as a verb:
* Please register for the conference online. (meaning to sign up or enroll)
* The cashier registered my purchase and gave me my receipt. (meaning to record a transaction)
* His voice registered surprise at the news. (meaning to show or express)
Register as a noun:
* She signed her name in the register. (meaning a book or list for recording names, etc.)
* The cash register was malfunctioning. (meaning a machine used to record and process transactions)
* His voice was high in register. (meaning the range of a voice or instrument)
Register as an adjective:
* The company had a large register of customers. (meaning a list or record of names)
* The painting is in the National Register of Historic Places. (meaning an official list of important places)
Let me know if you would like examples of any particular meaning of the word "register"!