= Synagoge sigma9, Photius sigma27 Theodoridis.
The glosses seem to reflect two distinct but similar-looking verbs, respectively LSJ s.v. sai/rw B ('sweep', 'clean') and LSJ s.v. sai/rw A ('gape'), which can apparently also mean 'laugh/smile insincerely' or the like. For the former cf. Hesychius sigma57; for the latter cf. Hesychius sigma445. Theodoridis follows Dindorf in suspecting that the second gloss has come to the entry intrusively from a entry pertaining to the latter verb. In any case, this form of the verb (present indicative active, third person singular) is unattested in either sense prior to the Suda (apart from lexicographical references).
For related words see sigma 143, sigma 144, and sigma 262 through sigma 264.