(1):
(n.) That which is behind, and forms the back of, anything, usually giving strength or stability.
(2):
(p. pr. & vb. n.) of Back
(3):
(n.) Support or aid given to a person or cause.
(4):
(n.) The preparation of the back of a book with glue, etc., before putting on the cover.
(5):
(n.) The act of moving backward, or of putting or moving anything backward.