n 1  cap  :  the type genus of the family Chlamydiaceae comprising coccoid to spherical gram-negative intracellular parasitic bacteria and including one (C. trachomatis) that causes or is associated with various diseases of the eye and genitourinary tract including trachoma, lymphogranuloma venereum, cervicitis, and some forms of nongonococcal urethritis  2  pl  -i*ae  also  -ias  a  :  a bacterium of the genus Chlamydia  b  :  an infection or disease caused by chlamydiae chla*myd*ial adj 
 
 
 
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