money demanded for the return of a captured person
"The kidnappers demanded a million dollars in ransom before they would release their hostage."
payment for the release of someone
"The kidnappers demanded a million dollars as ransom to free their victim."
the act of freeing from captivity or punishment
"The king agreed to release the captured nobleman once his family paid the demanded ransom."
Money paid for the freeing of a hostage.
"The kidnappers demanded a million dollars in ransom to release their captive daughter."
To deliver, especially in context of sin or relevant penalties.
"The priest explained that attending Mass on Sundays would ransom our souls from the penalty of missing God's grace."
A surname.
"The new headmaster, Mr. Ransom, greeted everyone with a warm smile upon his arrival."