stepping stone

noun

1. one of a series of stones acting as footrests for crossing streams, marshes, etc

2. a circumstance that assists progress towards some goal

Related Words

• aid 
• channel 
• equipment 
• factor 
• instrument 
• measure 
• mechanism 
• medium 
• mode 
• power 
• process 
• route 
• step 
• system 
• tactic 
• technique 
• vehicle