名詞 incest:

1. sexual intercourse between persons too closely related to marry (as between a parent and a child)

in.cest

n.（名詞）
Sexual relations between persons who are so closely related that their marriage is illegal or forbidden by custom.
亂倫：血緣過近而使其婚姻不合法或為風俗所禁止的人之間的性關(guān)系
The statutory crime of sexual relations with such a near relative.
亂倫罪：與這樣一個近親發(fā)生性關(guān)系的法定亂倫罪

來源：
Middle English
中古英語
from Latin incestum [neuter of] incestus [impure, unchaste]
源自 拉丁語 incestum [] incestus的中性 [不純潔的，不貞的]
in- [not] * see in-
in- [不] *參見 in-
castus [pure, chaste] * see kes-
castus [純潔的，貞潔的] *參見 kes-