وَلاَ تَقْرَبُواْ الْفَوَاحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ
and do not even draw near to things shameful - be they open or secret; (part of Verse 6:151)
The word fawahish applies to all those acts whose abominable character is self-evident. In the Qur'an all extra-marital sexual relationships, sodomy, nudity, false accusations of unchastity, and taking as one's wife a woman who had been married to one's father, are specifically reckoned as 'shameful deeds' (fawahish).
In Hadith, theft, taking intoxicating drinks and begging have been characterized as fawahish, as have many other brazenly indecent acts. Man is required to abstain from them both openly and in secret.