Gloss: ‘earth’ (item 10 in Bjørn 2017)
Hit. tēkan, HLuw. takam- (dat.-loc.sg.); Toch. A tkaṃ, Toch. B (t)keṃ; Lat. humus; OIr. dú; Goth. guma ‘man’; Lith. žẽmė; OCS zemlja; Alb. dhe; Gr. χθών; Ved. kṣás, Av. zam-.
This item harks back to the oldest layers of PIE with representation in most branches, including the decisive ancient Anatolian and Tocharian that further help establish the original sequence of the obstruents (D-G) that underwent metathesis sometime in late middle PIE (to G-D). This item has been mentioned as an argument in favor of Tocharian as the second branch to leave the PIE dialect continuum (cf. Kretschmer 1931).
Kartvelian: *diɣwam- ‘fertile soil’ > Georgian diɣvam– ‘black earth, sufficiency’ and Svan diɣwam ‘damp low place with f.’.
Kartvelian (alternative): *diqa- ‘clay’ > e.g. Georgian tixa, (?)Svan gim
Klimov proposes the connection with ‘fertile soil’ (1998: 41), which semantically seems a viable loan item due to its specialized meaning and formal triconsonantal quasiidentity (D-G-M), although the vocalism seems somewhat discontinuous; the labial
treatment of the IE velar similarly needs to be explained. These considerations would establish PIE as the provider of the term. Alternatively, Gamkrelidze & Ivanov suggest that the meaning ‘clay’ in Kartvelian may be related to PIE ‘earth’, and that the Svan form represent a simplified stem *ĝhem– < *dhĝhem– (1995: 774) to illuminate internal PIE development as well, but note that Klimov does not include Svan in this cognate set (1998: 72), reducing the reconstruction to Georgian-Zan, while Fähnrich treats it along with Mingrelian gim-e ‘below’ (2007: 107). This Svan form is, moreover, not an exact semantic parallelism, but the connotations in PIE with inherent association with ‘human’, e.g., at least some European languages, Goth. guma and Latin homō (cf. Mallory & Adams 1997: 366), could mend the comparison somewhat. The sequence of the obstruents in either Kartvelian comparandum would surely establish the loan to an early stratum of PIE, i.e. before the metathesis sometime after the presumed split of Tocharian. Kaiser & Shevoroshkin reject the hypothesis on formal grounds (1986: 368), but, all things considered, the connection with ‘black soil’ appears most attractive if the similarity is not merely due to chance resemblance.