Crotch
Groin
noun
The groin interval is simply the groin or crotch.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
股間がすごく痒い。
My crotch is really itchy.
あのダンサーはどうしていつも股間を押さえるの？
Why does that dancer always put his hand on his crotch?
恥ずかしいかもしれないけど、お医者さんに股間を見てもらったほうがいいと思うよ。
It might be embarrassing, but I think you should have your groin looked at by a doctor.