Sexpert（性學專家）是個合成詞，源于sex + expert。性學專家或性學大師還可以稱為sex therapist。

A person who professes a knowledge of sexual matters; A sex expert, especially a therapist who treats persons complaining of sexual dysfunction; Someone who has studied, or knows much about sex. This is the kind of person you can go to for advice and tips.
一個擁有性事方面專業知識的人；一位性方面的專家，尤指能為那些有性功能障礙人士提供咨詢的治療專家；這些人深入研究過性學，有很多這方面的知識，你可以向他們尋求建議和提示。

For example:
The sexpert would call this situation homosexuality.
性學專家把這種情形稱為同性戀。

That lady on the Sunday Night Sex Show is a sexpert.
參加《周日深夜秀》的那位女士是個性學專家。

（中國日報網英語點津 杜娟）