in‧ces‧tu‧ous /ɪnˈsestʃuəs/ adjective

1. involving sexual activity between people who are closely related in a family:
an incestuous relationship

2. involving a small group of people who only spend time with or help each other, not people outside the group – used to show disapproval:
an incestuous political community

[TahlilGaran] Dictionary of Contemporary English ▲