Sexually Transmitted Disease
Std
noun, の adjective
A gender sickness is one you catch from *ahem* doing things with those of another or the same gender. You only catch these sicknesses this way, meaning they're sexually transmitted diseases (save yourself some typing and just answer with STD).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
性病にかかってしまいました。
I have contracted a sexually transmitted disease.
性病にだけはゼッタイになりたくないんで。
Because I absolutely don't want to get a sexually transmitted disease.
彼氏に性病をうつされたんで、別れました。
I broke up with my boyfriend because he gave me a sexually transmitted disease.