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sexually transmitted disease n any of various diseases or infections that can be transmitted by direct sexual contact including some (as syphilis, gonorrhea, chlamydia, and genital herpes) chiefly spread by sexual means and others (as hepatitis B and AIDS) often contracted by nonsexual means called also STD
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(STD) an infection transmitted by sexual contact, either heterosexual or homosexual, caused by any of numerous biologically dissimilar pathogens; in some diseases (the classic venereal diseases) sexual transmission is the only important mode of spread, while in others (such as hepatitis, shigellosis, amebiasis, and giardiasis) infection can also be by nonsexual means. Called also venereal d.Medical dictionary. 2011.