All topics touched upon by people in the process of communication are divided into open and closed (forbidden). The forbidden topics includesubjects which are undesirable or unacceptable in the conversation. The open topics include subjects which are desired and acclaimed in the conversation. Each of these varieties of subjects comprises the whole amount of semantic and communicative identifying signs, specifically functions in the communicative space and demonstrates different ways of interaction with the diachronic and synchronous contexts. The characteristics of the subject’s openness and closedness can be detected at the level of a person, a group and a language community. The analysis of three different types of sources indicates that there is a single and computable list of twelve forbiddensubjects in English, Chinese and Russian. The closedness of the topic has less to do with a particular subject of discussion as with the assessment itself. The communication format, target setting and the degree of intimacy deform the idea of forbidden and open topics in specific situations of communication. The presence of a single list of closed topics in the languages of different systems once again points to the fundamental differences between the actual communicative and the actual language units and their relative independence from each other.