1. taking advantage of opportunities as they arise, often without regard for principles or consequences
2. caused by or taking advantage of a weakened condition
Usage: medical

Examples

• The politician made an opportunistic decision to switch parties when polls showed his support declining.
• She was criticized for her opportunistic behavior during the company crisis.
• The opportunistic investor bought stocks when prices crashed.
• Opportunistic infections often affect patients with compromised immune systems.
• His opportunistic approach to business made him wealthy but cost him friends.
• The bacteria caused an opportunistic infection in the weakened patient.