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

See also: important, of import

• ovenbird
• ovenware
• over
• over again
• over and over
• over and over again
• over here
• over my dead body
• over the counter security
• over the counter stock
• over-correct
• over-crowding
• over-egg
• over-embellished
• over-the-counter
• over-the-counter drug
• over-the-counter market
• over-the-counter medicine
• over-the-hill
• over-the-shoulder bombing
• over-the-top
• overabundance
• overabundant
• overachieve
• overachievement