1. Of or relating to a geological eon (longer than an era)
   - eonian [N. Amer] 
2. Continuing forever or indefinitely
   - ageless, eonian [N. Amer], eternal, everlasting, perpetual, unending, unceasing

See also: aeon, lasting, permanent

• spiny-leafed
• spiny-leaved
• spiny-stemmed
• SPipistrellus hesperus
• spiracle
• spiracular
• spiraea
• Spiraea prunifolia
• spiral
• spiral bandage
• spiral galaxy
• spiral nebula
• spiral ratchet screwdriver
• spiral spring
• spiral-shelled
• spiraling
• spiralling
• spirally
• spirant
• Spiranthes
• Spiranthes cernua
• Spiranthes porrifolia
• Spiranthes romanzoffiana
• Spiranthes spiralis
• spire