1. Sexual commerce within the prohibited degrees of matrimony.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• inscent,
• ancet,
• incerse,
• inces,
• concest,
• unlest,
• inist,
• incert,
• inocent,
• incast,
• inscect,
• unces,
• insyst,
• incesne,
• insest,
• inlist,
• inteset,
• accest,
• sincerst,
• incenst

• ingesta,
• injectant,
• in check,
• incessant,
• inexact,
• ingested,
• inachis,
• inquest,
• insectan,
• inexactly,
• injection,
• incus,
• invest,
• iciest,
• insecta,
• insistent,
• ingestion,
• ancestor,
• insect,
• inject,
• nicest,
• ingest,
• insisting,
• injustice,
• insist,
• in case,
• injector.

The adjective form of the word "incest" is "incestuous".

The plural of the "incest" can be the "incests".

The singular of the "incest" can be the "incest".