The primary headword appears to be the genitive of a masculine name, quoted from somewhere. The best-known Sinon is a 'character in literature and mythology, a Greek who claimed falsely to have deserted from the Greek forces at Troy and who inveigled the Trojans into taking the Trojan Horse inside the walls of Troy; he then later released the Greek heroes from the Horse and joined them in sacking the city' (OCD4 s.v.).
The extra material (missing from mss AF) then adds a feminine name (spelled with a varying number of n's), from Iamblichus, Babyloniaca. See already alpha 3179, sigma 789.