A semantic-motivational and etymological analysis of two Russian dialectisms ‘utin’ and ‘chemer’ are carried out in the article, in the semantic structure of which (among others) meanings associated with diseases of various localization and etiology (the authors are mainly interested in the semantics of low back pain) are presented. The semantic organization of the corresponding etymological and derivational nests is reconstructed; nests are matched by value configuration. The authors show what semantic transitions determined the appearance of the meaning «lumbar pain» (and, secondarily, «lower back» and «spine») in the words ‘utin’ and ‘chemer’. Both designations for low back pain are analyzed in a broad ethnolinguistic context, which implies taking into account the practices of traditional medicine, which are due to archaic ideas about pain and disease. It is shown that etymological magic is repeatedly triggered in the nest of the word ‘utin’, and its action is carried out in two directions: from the generating verb *tęti, *tьnǫ «cut down, cut» to the derivative ‘utin’, and then from it to other words of the morphosemantic field (‘utyug’, ‘utin’ «boundary», ‘utinok’ «stump», ‘ovin’, ‘tyn’ etc.). In the nest of the word ‘chemer’, a nontrivial transition of botanical meaning («poisonous plant») to physiological one («poisoning» → «pain in case of poisoning» → «pain of various etiologies, including lumbar pain») is restored, then (in parallel) to somatic and demonic.