Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. invŏcātus, a, um, Part., from invoco.
2. invŏcātus, a, um, adj. [2. in-voco].
3. in-vŏcātus, ūs, m. (only in abl. sing.), a non-summoning: si injussu atque invocatu meo (verba) venerint, without my summons, Fronto ad Verum, ep. 1.