The primary headword is present middle infinitive of foiba/w.
[1] = Hesychius phi679, Synagoge phi149, Photius phi236 Theodoridis. As Latte suggests in his edition of Hesychius, perhaps from commentary to Cyril of Alexandria, De adoratione et cultu in spiritu et veritate PG 68.448.11, the only surviving literary attestation of the headword form.
[2] Two forms of the adjective foi=bos (cf. phi 780), from which the primary headword derives, are glossed in this supplementary sentence: the neuter singular nominative/accusative and the feminine plural nominative. The combination identifies the context as being similar to what we find in Etymologicum Gudianum 555.38-39, where the neuter lemma is a generic lexical reference used to explain the use of the feminine plural form to modify the word for hairs (cf. also Etymologicum Magnum 797.1). Non-lexicographical attestations of that application of the term are lacking, and there is perhaps some confusion between it and the lookalike word fo/bai ('locks of hair'). In general, forms of foi=bos are frequently glossed with forms of kaqaro/s ('pure'), e.g. Orion [Author, Myth] 157.1-2, Hesychius phi683.