duration (n.)

• age
• antiquity
• changelessness
• chronology
• constancy
• continuance
• continuation
• continuity
• durability
• endurance
• firmness
• fixedness
• hardening
• immobility
• immovability
• immovableness
• immutability
• invariability
• invariableness
• lastingness
• longevity
• maintenance
• perdurability
• perennation
• period
• permanence
• permanency
• perpetuity
• persistence
• persistency
• quiescence
• rigidity
• run
• solidity
• space
• space-time
• span
• spell
• stability
• standing
• stasis
• steadfastness
• survival
• tense
• tenure
• term
• tide
• time
• torpor
• unchangeability
• unchangingness
• while