Does the thick white fluid that exits the penis upon thinking of women necessitate ghusl or defile the body or clothing, and what is the name of this fluid, and what is the best way to get rid of these thoughts?

One must not surrender to lustful thoughts and whisperings, especially if they are forbidden and lead to desire, for this is considered a form of zina (fornication/adultery), as stated in the Hadith (definition): "The heart yearns and desires, and the private parts either confirm or deny that." One should occupy oneself with what benefits in matters of religion and worldly life, and utilize the blessing of the intellect in what pleases Allah, for Allah will question about this blessing. As for what exits in this situation, it is most likely madhy (pre-seminal fluid), and one should refer to Fatwa (definition) no. 32023 for the difference between madhy and maniy (seminal fluid).