Science fiction depicts worlds that often differ greatly from the real one. These worlds may be set in the remote future and so consist of elements unfamiliar to the reader. The names of those elements may be untypical or, conversely, they may be typical but denote unexpected referents. However, the border between a fictional world (even the most fantastic one) and reality is not as thick as it seems to be. A similar relation exists between the original and target texts. The article deals with Stanisław Lem’s neologisms that occur in his novel Memoirs Found in a Bathtub and their translation into English. The real and literary world are understood as two borderlands and translation is viewed as creating a third one. The border is set by the author who, in order to separate the real from the fantastic, uses new words and expressions to name the elements of the narrative world. The translators, whose intention is to supply the text to the target reader, decode and render these names in various ways, and by doing so often change the shape of a given border.