[5] Heiðornir (m.): This is another name for the lowest heaven. The first element of the cpd is heið- ‘bright’, but the form and the meaning of the second part is obscure. The mss of the þula have three variants. (a) The A, B variant -ornir (so also ms. A(14r) of Skm; adopted in the present edn, as well as in Skj B and Skald) is possibly derived from the weak verb orna ‘get warm’; hence ‘one warming itself in brightness’ (cf. ornir ‘one warming itself’, Þul Orma 1/8). (b) Ms. R has -yrnir (cf. Skatyrnir, l. 19). Falk (1925b, 36) suggests that the latter name could have served as a model for Heiðyrnir, which, in his opinion, would denote the bright sky. (c) Mss Tˣ, C have -þyrnir (and this is also the form given in the prose list in Skm in U(36v) (‘heiþ þyrnir’); cf. Heið<þ>yrnir in SnE 1998, I, 133), but ‑þyrnir, a derivative from þorn m. ‘thorn’, is hardly appropriate as an element of the name for ‘sky’. (d) In the list of heaven-heiti in some mss of Skm the heiti is found in the form -þornir (adopted in SnE 1998, I, 85; cf. ‘heið\þ/ornir’ R(37r), ‘heidþor-nir’ Tˣ(38v), ‘heiðþornir’ C(6r); explained as ‘bright-clouded’ in SnE 1998, II, 304). It has been suggested that ‑þornir could have originated from the strong verb þverra (p. p. þorrinn) ‘wane, decrease’ (hence possibly ‘one whose brightness has decreased’, perhaps denoting the cloudy sky) or may be related to the weak verb þorna ‘become dry’ and ModIcel. þyrrinn ‘dry’ (cf. ÍO: heiðornir, heiðyrnir, heiðþyrnir).