The headword (extracted from the first of the quotations given but also illustrated by the second) is the present active imperative, second person singular, of the contract verb strobe/w, I whirl, twirl about; cf. sigma 1205 and see generally LSJ s.v.
[1] These initial glossing verbs are also second person singular imperatives, respectively from a)nakri/nw (I examine closely, interrogate) and dokima/zw (I assay, test); see generally LSJ s.vv.
[2] Following a scholion (= scholia vetera) to the Aristophanic passage about to be quoted: see next note.
[3] Aristophanes, Clouds 700-702 (web address 1); Dover, pp. 186-8, esp 188. The chorus urges Strepsiades to think for himself (e.g. concentrate on his own problem), as he twists and turns (and perhaps curls or concentrates himself into a ball) while the bedbugs are biting at him. [In her critical apparatus Adler reports that mss GM omit dh\ (emphatic now); also that ms G lacks sauto\n (yourself).]
[4] Aristophanes, Knights 387-388 (web address 2), with scholion to 388. The chorus cheer on the sausage-seller, who is locked in a demagogic debate with Paphlagon (= Kleon: kappa 1731, and Develin no. 1659, p. 476).