1. Vitally important
   - life-and-death

See also: crucial, important

• introspective
• introspectively
• introspectiveness
• introuvable
• introversion
• introversive
• introvert
• introverted
• introvertish
• introvertive
• intrude
• intrude on
• intruder
• intruding
• intrusion
• intrusive
• intrusiveness
• intrust
• intubate
• intubation
• intuit
• intuition
• intuitional
• intuitionism
• intuitionist