形容词

1. For most people, birth control is no longer such a taboo subject.
对大多数人来说，节制生育已不再是那么一个禁忌的话题。

名词

1. A taboo against sex before marriage.
婚前禁止性行为。

1. 禁忌;忌讳
If there is a taboo on a subject or activity, it is a social custom to avoid doing that activity or talking about that subject, because people find them embarrassing or offensive.

e.g. The topic of addiction remains something of a taboo...
毒瘾仍然是个有些忌讳的话题。
e.g. Religious dogmas often include strong sexual taboos and can create in children the impression that sex is sinful.
宗教教义中经常包含严格的性禁忌，这会给儿童留下“性是罪恶”的印象。

noun

1. an inhibition or ban resulting from social custom or emotional aversion

Synonym: tabu

2. a prejudice (especially in Polynesia and other South Pacific islands) that prohibits the use or mention of something because of its sacred nature

Synonym: tabu