The headword is the neuter nominative (and vocative and accusative) singular (and masculine accusative singular) form of the verbal adjective parete/os (Smyth, 358.2; LSJ s.v. parete/on), derived from the verb pari/hmi, I drop alongside; see LSJ s.v., and pi 347, pi 649. The headword occurs at, for example, Plato, Laws 796A (web address 1) and 796B (web address 2), and Aristotle, Nicomachean Ethics 1172a26 (web address 3).
[1] The first gloss is the neuter nominative (and vocative and accusative) singular (and masculine accusative singular) form of the verbal adjective siwphte/os; see LSJ s.v.
[2] The second gloss does not appear to support the headword. It is the neuter nominative (and vocative and accusative) singular (and masculine and feminine accusative singular) form of the verbal adjective paralhpte/os, coming from the verb paralamba/nw; see LSJ s.v. and cf. Demosthenes 34.30 (web address 4). Probably, as Gaisford suggested, the lexicographer intended the verbal adjective paraleipte/on, that must be passed over, derived from the verb paralei/pw. The meaning of this last verbal adjective corresponds to the sense of the headword, and it is homophonous in later Greek with paralhpte/on.