Get a Latin Tutor
Latin word firmamentum comes from Proto-Indo-European *dʰerw-, and later Latin firmus (Faithful, steadfast, true. Stable, strong, firm.)
*dʰerw- (Proto-Indo-European)
cloudiness, dirt; to dim, darken, tarnish, dull, to hold, hold tight, support
*dʰer-mo-s (Proto-Indo-European)
holding
firmus (Latin)
Faithful, steadfast, true. Stable, strong, firm.
firmare (Latin)
firmamentum (Latin)
A strengthening, support, prop, stay.. The firmament; the sky fixed above the earth.. The main point or crux (of an argument).