sexual intercourse between persons too closely related to marry (as between a parent and a child)
"The family scandal erupted after it was revealed that the couple had engaged in incest, violating every moral and legal boundary by sleeping together despite being half-siblings."
Sexual relations between close relatives, especially immediate family members and first cousins, usually considered taboo; in many jurisdictions, close relatives are not allowed to marry, and incest is a crime.
"The court ruled that the secret marriage between the siblings was a criminal act of incest under local law."
In plain English: Incest is when family members who are too closely related have sexual relationships with each other.
"The scandal involved allegations of incest within the royal family."
Usage: Incest refers specifically to sexual activity or marriage between close blood relatives, such as parents and children or siblings. This term describes a relationship that is socially taboo and often illegal, distinct from general familial closeness.
To engage in incestuous sexual intercourse.
"The family feud escalated after it was revealed that the two cousins had engaged in incest."
"No family member should ever be allowed to incest with anyone else in their own household."
Usage: Incest is not used as a verb in standard English; instead, use the noun phrase "commit incest" or simply "engage in incest." The word itself functions only as a noun describing the act of having sexual relations with close family members.
The word incest comes from the Latin term incestus, which originally meant "unlawful" or "immoral." It entered Middle English as a learned borrowing, eventually replacing the Old English phrase mǣġhǣmed, literally meaning "relative-sex," to describe sexual relations between close family members.