The headword adjective occurs in hellenistic poetry, e.g. Callimachus and Nicander, and it is similarly glossed in the scholia to the latter (Theriaca 689); see also Hesychius lambda123 and lambda124. (Both of these Hesychius entries also associate the word with a)ristera/ or a)ristero/s, one of several terms meaning 'left'; cf. lambda 174, lambda 193. Did the lexicographer searching Hesychius or a similar author for lai- words, associate the present adjective, laidro/s with laio/s, 'left', because they stood in proximity to one another?)
[1] The definite article before qrasu/s seems only to identify it as masculine, nominative singular.