1. Any of a group of microorganisms of the genus chlamydia that are obligate intracellular parasites and include the causative agents of trachoma psittacosis and lymphogranuloma venereum.
2. Any of a group of microorganisms of the genus chlamydia that are obligate intracellular parasites and include the causative agents of trachoma psittacosis and lymphogranuloma venereum.