taboo

1. N-COUNT A taboo against a subject or activity is a social custom to avoid doing that activity or talking about that subject, because people find them embarrassing or offensive. 禁忌

The topic of addiction remains something of a taboo in our family. 毒癮在我們家依然是個有些忌諱的話題。

2. ADJ Taboo is also an adjective. 禁忌的

Cancer is a taboo subject and people are frightened or embarrassed to talk openly about it. 癌症是個禁忌的話題，人們對公開談論它感到害怕或尲尬。