Same entry elsewhere: see the references at Photius sigma821 Theodoridis, where the editor supports Naber's suggestion that the headword (present middle participle, masculine nominative singular, of sunwqe/w) is quoted from Plato, Timaeus 59A. (Other possibilities include Appian, Libyca 541.)
[1] Adler notes Bernhardy's suggestion that the glossing participle be emended from sunerxo/menos to sunergo/menos "being worked together".