The unglossed headword (evidently quoted from somewhere) is aorist indicative passive, third-person plural, of the verb plinqeu/w (on which see pi 1772, pi 1773). This form is unattested outside lexicography, and no other form of the verb is attested with the connotation ascribed to it here. But a similar gloss of the same form at Lexica Segueriana 253.8-12 (Glossae rhetoricae; cf. Lex.Seg., *dikw=n o)no/mata 187.27, Etymologicum Magnum 367.43) suggests that the original context was in the corpus of one of the classical Athenian orators.
Note LSJ s.v. plinqeu/w, III: 'Pass. is variously expld. by Gramm. as to be changed into bricks, built up with bricks, tortured or enslaved, EM367.43 etc.; to be duped, Hsch., Suid.'. See also Photius, Lexicon epsilon1818, canvassing four possible interpretations!
[1] In place of the (at best) awkward phrase peri\ oi)kodo/mhma mo/non (translated here as "alone in the confines of a structure") Bekker suggests substituting the participle periw|kodomhme/non, which would make the Greek a bit more clear and alter the translation as follows: "being shut up by having a structure built around one..." This emendation receives some support from the parallel entry in the Glossae rhetoricae (see note above), where a different form of this verb is employed (perioikodomhqe/ntes).