1. Nearest in space or position; immediately adjoining without intervening space
   "our rooms were side by side"
   - adjacent, next 
2. Closely related or associated
   "a city in which communism and democracy had to live side by side"

See also: close, related, related to

• white ash
• white aspen
• white avens
• white backlash
• white baneberry
• white basswood
• white bead
• white bean
• white bedstraw
• white beech
• white beer
• white birch
• white blood cell
• nitrogen cycle
• nitrogen dioxide
• nitrogen fixation
• nitrogen mustard
• nitrogen narcosis
• nitrogen oxide
• nitrogen trichloride
• nitrogen-bearing
• nitrogen-fixing
• nitrogenase
• nitrogenise
• nitrogenize