1. Not recurring at regular intervals
   - aperiodic

See also: noncyclic, nonoscillatory

• subway
• subway fare
• subway station
• subway system
• subway token
• subway train
• subwoofer
• subzero
• succade
• succedaneous
• succedaneum
• succeed
• succeeder
• succeeding
• success
• success story
• successful
• successfully
• successfulness
• succession
• successional
• successive
• successively
• successiveness
• successor