Traditional etymological reconstructions show that in a quite close-knit European area many words denoting the social aggregation of ‘people’ and ‘crowd’ derive from stems with similar meaning, linked to notions ranging from ‘fullness’ to ‘swelling’. In this paper some words deriving from the reconstructed form *teuṱ eh2 (<*teṷH- / tuH-) are analyzed and special attention is paid to the Greek and Latin words τὸ πλῆθος / ἡ πληθυ�ς, plēbs / plēbēs (<*pelh1-). Etymological reconstructions proposed thus far are set out and discussed, with special attention to the phonological and morphological structure of the words at issue. Moreover, the hypothesis that the words derived from *teutā have not an Indo-European origin, but rather belong to the so called “North- West vocabulary” is addressed. New insights into the etymological reconstruction of the terms at issue are provided by assigning a key role to the semantic content. First of all, the socio-institutional meaning of the terms is assessed by taking into account both linguistic evidence and historical reconstructions. Second, the semantic development that led from the meaning “swelling”, “fullness” of the two stems *teuh̭ 2- / tuh2- and *pelh1- to the meaning “folk, people” is interpreted in the light of the cognitive notions of ‘metaphor’ and ‘metonymy’.