This article presents the results of a linguistic-cognitive analysis of selected Polish and German terms that indicate medical diseases or disorders that, in addition, include elements that refer to plants. The aim of the analysis is to examine the equivalence between the medical terms used in both languages with respect to the linguistic worldview generated by the specific language, and that is symptomatic of its material cultural. It is concluded that in most cases of terms indicating medical illnesses or disorders there either is a full or partial equivalence between the Polish and German terms. The examined equivalence can be helpful not only in the foreign language learning/teaching but also in the contact between a doctor and his patient. Thus, the searched isomorphism can be regarded as a factor which supports both the process of language learning/teaching and the understanding of a partner in the communication process and the reception of the delivered meaning.