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

• sleep around
• sleep deprivation
• sleep disorder
• sleep in
• sleep late
• sleep off
• sleep out
• sleep talking
• sleep terror disorder
• sleep together
• sleep with
• sleep-learning
• sleeper
• sleeper cell
• sleeper goby
• sleeper nest
• sleepily
• sleepiness
• sleeping
• sleeping accommodation
• sleeping around
• sleeping bag
• sleeping beauty
• sleeping capsule
• sleeping car