Zināʾ (زِنَاء) or zinā (زِنًى or زِنًا) is an Islamic legal term referring to unlawful sexual intercourse. According to traditional jurisprudence, zina can include adultery, fornication, prostitution, rape, sodomy, incest, and bestiality. Zina must be proved by testimony of four Muslim eyewitnesses to the actual act of penetration, or a confession repeated four times and not retracted later. The offenders must have acted of their own free will. Rapists could be prosecuted under different legal categories which used normal evidentiary rules. Making an accusation of zina without presenting the required eyewitnesses is called qadhf (القذف), which is itself a hudud offense.

There are very few recorded examples of the stoning penalty for zinā being implemented legally. Prior to legal reforms introduced in several countries during the 20th century, the procedural requirements for proving the offense of zinā to the standard necessary to impose the stoning penalty were effectively impossible to meet.

Zina became a more pressing issue in modern times, as Islamist movements and governments employed polemics against public immorality. In recent decades several countries passed legal reforms that incorporated elements of hudud laws into their legal codes, and many modern Islamists have also disregarded the condition of strict evidence requirements. In Nigeria, local courts have passed several stoning sentences, all of which were overturned on appeal or left unenforced. In Pakistan, the Hudood Ordinances of 1979 subsumed prosecution of rape under the category of zina, making rape extremely difficult to prove and exposing the victims to jail sentences for admitting illicit intercourse forced upon them, although these laws were amended in 2006, and again in 2016. According to human rights organizations, stoning for zina has also been carried out in Saudi Arabia.