noun

• The act of preventing or hindering; obstruction of action, access, or approach; thwarting.
• (medicine) Any measure intended to limit health-related risks (such as information campaigns, vaccination, early diagnosis etc.).
• (obsolete) The act of going, or state of being, before.
• (obsolete) Anticipation; especially, anticipation of needs, wishes, hazards and risks
• precaution; forethought.