indeclinabilis
From LSJ
τίς γὰρ ἁδονᾶς ἄτερ θνατῶν βίος ποθεινὸς ἢ ποία τυραννίς; τᾶς ἄτερ οὐδὲ θεῶν ζηλωτὸς αἰών → What human life is desirable without pleasure, or what lordly power? Without it not even the life of the gods is enviable.
Latin > English (Lewis & Short)
in-dēclīnābĭlis: e, adj.,
I inflexible, unchangeable, only in a trop. sense (postAug.).
I In gen., of things: virtus animum rectum et indeclinabilem praestat, Sen. Ep. 66: justitia, id. ib. 74: series re rum, Gell. 6, 2.—Of persons: judex, Amm. 25, 4; id. 18, 1.—
II In gram.: nomen, indeclinable, Diom. pp. 288, 289 P. — Hence, indēclīnābĭlĭter, adv., unchangeably, Aug. Civ. Dei, 9, 22 fin.