The article deals with the language semantic units and peculiarities of their performance from the point of view of linguistics. The author highlights how the semantic unit application in a certain function (name-word or symbol-word) influences the speech efficiency of the politician supplementing his/her political image. We investigated a symbol-word as a semantic unit with inherent psychological and linguistic features which lie in the fact that the properties of the object are manifested; its main and additional meaning as well as feelings are expressed through the language means. By segregating the differences of the symbol-word from other semantic units we defined its main functions in the political speech that make it possible for the text to turn into a powerful tool of influence on the listener's consciousness. Due to the analysis of the words in the function of respective semantic units we were able to realise certain mechanics of the impact on the recipient's (public) consciousness and to assess their role in the efficiency of emphasis in the speech and the possibility of getting an emotional response from the listener. We defined the aspects enabling the political speech to increase influence on the audience. Firstly, the use of symbol-words in the speech of a politician makes it possible to build the speech addressed not to the rational thinking but affects an unconsciousness suggesting stable meanings. Secondly, with the help of symbols the most vulnerable fields of consciousness are affected, which in turn can trigger strong emotions (fear, anxiety, hope, etc.). Based on the analysis of the speech by Donald Trump, we demonstrated how the change of semantic unit function from the name word to the symbol-word is capable of distinguishing emphasis that increases the efficiency of influence on the public consciousness.