(n): an increase by natural growth or addition
(n): someone who takes the place of another (as when things get dangerous or difficult)
(n): a person who is of equal standing with another in a group
(n): a musical part (vocal or instrumental) that supports or provides background for other musical parts
(n): the melody carried by a particular voice or instrument in polyphonic music
(n): (computer science) a copy of a file or directory on a separate storage device
(n): a copy that corresponds to an original exactly
(n): the act of providing approval and support
(n): the formal act of approving
