trichomonas

trichomonas A single-celled protozoan parasite best known in medicine because one species causes vaginitis (vaginal inflammation). The species of trichomonas responsible for the sexually transmitted disease is Trichomonas vaginalis. The vagina is the most common site of infection in women, and the urethra (urine canal) is the most common site of infection in men. See also trichomoniasis.