LSJ records for the epic/poetic neuter noun lai=fos the two senses "shabby garment" and "canvas, sail". The dative given here in the Suda is to illustrate that this is a third declension neuter and not a second declension masculine. Of the other lexica, Herodian (Partitions p. 76 Boissonade), the Etymologicum Gudianum, the Etymological Genuinum, the Etymologicum Magnum, ps.-Zonaras and Gennadius Scholarius, Grammar p. 463, all define it as just "sail" (with the folk etymology li/an fai/nesqai "very much to be seen"); Apollonius' Homeric Lexicon and Hesychius as just "cloth" (with one ms of Hesychius adding "namely, sail"); and the Synagoge, Photius, and the Lexica Segueriana as just "outer-garment". The Suda has combined them all. Theognostus, On Orthography 27, and ps.-Zonaras also define it as xlai=na "cloak".