The headword is perfect participle, masculine nominative singular, of the verb stu/w (on which see generally J. Henderson, The Maculate Muse (New Haven 1975) 112 #7). It is presumably extracted from the quotation given here, though there are also three instances in Aristophanes (Lysistrata 214 & 215, Thesmophoriazusae 158)
[1] Comica adespota fr.598 Kock (now 520 K.-A.). For a slightly different (and metrically superior) version see omicron 810.