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

See also: important, of import

• mail merge
• mail order
• mail out
• mail pouch
• mail service
• mail slot
• mail train
• mail-cheeked
• mail-clad
• mail-order buying
• mailbag
• mailboat
• mailbox
• maildrop
• mailed
• mailer
• mailing
• mailing address
• mailing list
• mailing-card
• Maillol
• maillot
• mailman
• mailshot
• mailsorter