1. Serving or acting as a means or aid
   - instrumental, subservient

See also: helpful, implement

• substitutive
• substract
• substrate
• substratum
• substring
• substructure
• subsume
• subsumption
• subsurface
• subsystem
• subtenant
• subtend
• subterfuge
• subterminal
• subterranean
• subterraneous
• subtext
• subthalamic nucleus
• subthalamus
• subtile
• subtilin
• subtilise
• subtilize
• subtitle
• subtle