The headword is the aorist participle, masculine nominative singular, of the uncommon compound verb suntekmai/romai, I altogether judge (literally: put to the test of proof); see LSJ s.v. It is presumably extracted from the quotation given, a participial phrase without context or even a main verb.
For the uncompound tekmai/romai, cf. tau 243 and tau 244.
[1] The first gloss is the aorist active participle, masculine nominative singular, of the verb sumba/llw, literally I throw together; see LSJ s.v. The second gloss is the aorist participle, masculine nominative singular, of the verb katastoxa/zomai, I aim at, infer; cf. kappa 797 (present indicative, third person singular) and see LSJ s.v.
[2] Eunapius fr. 99 FHG (4.54); Blockley, pp. 126-7.