1. Of the greatest importance
   "in chess cool nerves are of the essence"
   - all-important, all important, crucial, essential

See also: important, of import

• self-propelled
• self-propelled vehicle
• self-propelling
• self-protection
• self-punishment
• self-raising flour
• self-realisation
• self-realization
• self-referent
• self-referential
• self-reformation
• self-regard
• self-registering thermometer
• self-regulating
• self-regulation
• self-regulatory
• self-reliance
• self-reliant
• self-renewal
• self-renewing
• self-renunciation
• self-report inventory
• self-report personality inventory
• self-reproach
• self-reproof