precursor /prē-kûrˈsər/

1. Something that exists or goes in advance of another
2. An indication of the approach of an event
3. A forerunner, herald or harbinger
4. A predecessor
5. A substance from which the one in question is derived or manufactured (chem)

• red snappers
• red snow
• red spider
• red spider mite
• red spider mites
• red spiders
• red squirrel
• red squirrels
• redstart
• redstarts
• redstreak
• redstreaks
• reds under the bed
• reds under the beds
• red tape
• red-tape
• red-tapism
• red-tapist
• red-tapists
• red tide
• red tides
• red-top
• redtop
• red-tops
• redtops