To ally oneself, be in an alliance, usually with "with" or rarely "in with"
Which will you side with, good or evil?
To lean on one side.
To be or stand at the side of; to be on the side toward.
To suit; to pair; to match.
To work (a timber or rib) to a certain thickness by trimming the sides.
To furnish with a siding.
to side a house
To provide with, as a side or accompaniment.
To clear, tidy or sort.