The unglossed headword is presumably extracted from the quotation given, where context makes it a genitive plural form. Its meaning here is uncertain. Besides being a well-attested woman's name, a plaggw/n is defined by Hesychius s.v. as a wax doll (which is the meaning it bears in e.g. Callimachus, Hymn to Demeter 92); however, he adds kai\ plaggo/nes kekru/faloi -- "also, plangones are women's hair-nets".
In her critical apparatus Adler notes that mss AF transmit *plago/nwn, although a later hand corrected this within ms A; also that the rest of the entry is lacking in ms F.
[1] The quotation, again at sigma 1154 and in part at tau 688, is unidentifiable. Adler notes Cobet's attribution of it to Aelian. Adler also notes that mss AM (after correction) here transmit the alternative spelling plago/nwn for the headword.