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)

• aplanatism
• aplanatisms
• aplanats
• aplanogamete
• aplanogametes
• aplanospore
• aplanospores
• aplasia
• aplasias
• aplastic
• aplastic anaemia
• aplenty
• aplite
• aplites
• aplomb
• aplombs
• aplustre
• aplustres
• apnea
• apneas
• apnoea
• apnoeas
• apo.
• Apoc.
• apocalypse