Meaning

• (frequency) One and only one time.

  "I have only once eaten pizza."

• (temporal location) Formerly; during some period in the past.

  "He was once the most handsome man around."

• Multiplied by one: indicating that a number is multiplied by one.

  "Once three is three."

• As soon as.

• At a future time.

Meaning

• As soon as; when; after.

  "Once he is married, he will be able to claim the inheritance."