1. Serving as an introduction or preface
   - introductory, prefatorial

See also: preceding

• activated charcoal
• activating
• activating agent
• activation
• 39th
• 3d radar
• 3rd
• 3rd October Organization
• 3TC
• 4
• 4-dimensional
• 4-hitter
• 4-membered
• 40
• 400
• 400th
• 401-k
• 401-k plan
• 40th
• 41
• 41st
• 42
• 42nd
• 43
• 43rd