Of the utmost importance; crucial.
Formed by combining the words "all" and "important".
- The meeting was all-important, as the future of the company depended on its outcome.
- He considered his education to be all-important in his career.
- The all-important question of the evening was when the guests would arrive.
- Her wedding day was the all-important event of her life.
- The all-important goal is to reduce the number of accidents on the highway.