1
general::
Phrase(s): side by side
(of two or more people or things) lined up so their sides are adjacent. • We walked side by side across the lawn.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Next to each other, close together, as in They were walking down the street side by side when the taxi jumped the curb, or In the new Russia communism and capitalism are trying to live side by side. [c. 1200]
American Heritage Idioms