1. between — de Vaan
between 'dormouse' and 'weasel' also mars the comparison with Skt. giri'sister-in-law' < *glh2-i-, which would formally be attractive. Cuesta Pastor (1996) argues that the Gr, gloss γάλις 'husband's sister' together with Skt giri- and Arm. to/, points to a PIE stem *glh2-i- 'sister-in-law', and, since 'aunt' is often used metaphorically for 'weasel', Latin glis can represent the same PtE stem. Oettinger 1998, too, … — [de Vaan, s.v. between, p. 278]
2. between — de Vaan
between 'breast' and 'pride', and between 'breast' and 'large', is gratuitous. Vennemann 1998b proposes to regard grandis and Basque handi 'big' as two survivors of an earlier Vasconian substrate; yet the number of ad hoc assumptions which is necessary to explain the Basque side of this comparison is rather large. BibL: WH I: 617f, EM 281, IEW 485. grande, -inis 'hail' [f. n\ (P1.+) Derivatives: grandinat 'it hails' … — [de Vaan, s.v. between, p. 284]
3. between — de Vaan
between 'to believe' and 'to choose' is weak, and so is therefore the traditional etymological connection with the root of optare. Vine 1999a argues that it is difficult to reconstruct a stem *opion-/*opion-fromwhich ορϊη-ά- could have been derived, as others had proposed. He argues that the Praenestine spelling opeinor in a third-century inscription proves that the word contains Pit. *-eJ- and not even *-f-, which … — [de Vaan, s.v. between, p. 444]
4. between — de Vaan
between 'grey' and 'swamp' is uncompelling. BibL: WH II: 243, EM 478, IEW 798-801, Schrijver 1991: 210f. pandu, -ere 'to spread out, extend' [v. Ill; ppp. possum] (Naev.+) Derivatives: pandiculan 'to contort one's face in a grimace' (P1.+), passus 'extended, free; dry, wrinkled' (Naev.+), passim [adv.] 'here and there, indiscriminately' (P1.+), possum 'raisin-wine' (PL+), passus, -us 'step, pace' (PL+), — [de Vaan, s.v. between, p. 456]