1. a thick-walled structure containing a fertilized egg cell, especially in parasitic protozoans
Usage: biology

Examples

• The oocyst stage allows the parasite to survive harsh environmental conditions.
• Scientists examined oocysts under the microscope to study the parasite’s life cycle.
• Contaminated water may contain oocysts that can cause infection.
• The oocyst wall protects the developing organism inside.
• Researchers counted oocysts in the soil samples to measure contamination levels.