Source: https://fo.sina.com.cn/book/wj/2012-11-06/13172947.shtml?from=wap

定的名称，在梵语中，除了三昧，尚有七名：三摩地、三摩钵底、三摩呬多、驮那演那、奢摩他、现法安乐、质多医迦阿羯罗多等等，正因为定境通于凡圣，致有印度人，认为男女性交，也叫三摩钵底──雌雄等至，因那时也有心意集中，淫乐遍身，类似定心的现象。至于那些说什么性命双修啦，身心双修啦，就是想从男女的淫乐中修定(见印顺法师成佛之道一四四页)。修定的意义，被附会混杂到如此的猥亵下流，也真可悲可怜！但是，这也告诉了我们，印度对于定的意义是看得非常广泛的，这与中国禅宗的本旨，何止相去天渊！

[Google translate:]
　　In Sanskrit, besides Samadhi, there are seven other names for concentration: Samadhi, Samadhi, Samadhita, Danayanna, Shamatha, Xianfa Anle, Jitayijia Akarada, etc. Because the state of concentration is common to both ordinary people and saints, some Indians believe that sexual intercourse between men and women is also called Samadhi – equal concentration of male and female, because at that time, the mind is also concentrated, and sexual pleasure permeates the body, which is similar to the phenomenon of concentration. As for those who say that they practice both sex and life, and both body and mind, they just want to cultivate concentration through sexual pleasure between men and women (see Master Yinshun’s Path to Buddhahood, page 144). It is really sad and pitiful that the meaning of cultivating concentration has been mixed up to such an obscene and vulgar meaning! However, this also tells us that India has a very broad view of the meaning of concentration, which is far from the original purpose of Chinese Zen!