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

• trace detector
• trace element
• trace fossil
• trace program
• traceable
• tracer
• tracer bullet
• tracery
• trachea
• tracheal
• tracheal vein
• tracheid
• tracheitis
• Trachelospermum
• Trachelospermum jasminoides
• tracheobronchitis
• Tracheophyta
• tracheophyte
• tracheostomy
• tracheotomy
• Trachinotus
• Trachinotus carolinus
• Trachinotus falcatus
• Trachipteridae
• Trachipterus