Lexical Definition

‎στερεός‎ stereós (ster-eh-os') strong ^G:A
from ‎ἵστημι‎

stedfast, strong, sure.

• stiff, i.e. solid, stable (literally or figuratively)

Abbott-Smith

στερεός, -ά, -όν [in LXX: Nu 8:4 (מִקְשָׁה); σ. πέτρα, Is 5:28 (צַר), etc. ;]
hard, firm, solid: τροψή, He 5:12, 14; θεμέλιος, fig., II Ti 2:19. Metaph.,
(a) in bad sense, hard, cruel (Hom., al.);
(b) in good sense, steadfast, firm: τ. πίστει, I Pe 5:9.†

Abbott-Smith References

Liddell-Scott-Jones

στερεός, ά, όν,

also στερρός (which see), firm, solid, σ. λίθος ἠὲ σίδηρος [Refs 8th c.BC+]; αἰχμὴ σ. πᾶσα χρυσέη all of solid gold, [Refs 5th c.BC+]; τὰ -ώτερα τῶν ὀστέων, opposed to τὰ ἀραιότερα, [Refs 5th c.BC+]; τὸ σ., opposed to κενόν, [Refs 4th c.BC+]; opposed to μαλθακός, [Refs 5th c.BC+]; κυσὶ σ. καὶ ἰσχνοῖς, opposed to προβάτοις πίοσι καὶ ἁπαλοῖς, [Refs 5th c.BC+]; σ. κέρας solid, opposed to κοῖλον, [Refs 4th c.BC+]; στερεὰ τροφή solid food, [NT+1st c.BC+]; τὸ σ. σῶμα, opposed to ὁ χυλός, [Refs 2nd c.AD+]; σ. κοιλίη costive, [Refs 5th c.BC+]. adverb -ρεῶς firmly, fast, κατέδησαν [Refs 8th c.BC+]

__b of money, standard, of full value, ἀργυρίου στερεὰ τάλαντα [Refs 2nd c.BC+]; so perhaps of sums due in kind, πυροῦ στερεοῦ [Refs 2nd c.BC+]; and of linear and square measures, τῆς προσούσης αὐλῆς πηχῶν σ. ὀκτὼ τὸ ἐπιβάλλον αὐτῷ μέρος ἥμισυ πήχεις σ. τέσσερας eight (four) standard cubits, [Refs 2nd c.BC+]; πόδες σ. standard feet, [Refs]; μέτρημα σ. [Refs 3rd c.BC+]
__c ὠρύγη ποταμὸς ἐπὶ τὰ τρία σ. the ditch was restored by digging to its three normal dimensions, [Refs 1st c.AD+], compare 673, where the Latin version has at tria soldu (m).
__2 metaphorically, stiff, stubborn, στερεοῖς ἐπέεσσι, opposed to μειλιχίοις, [Refs 8th c.BC+]. adverb -ρεῶς, ἀποειπεῖν [Refs 8th c.BC+]
__3 later, hard, stubborn, cruel, πῦρ [Refs 5th c.BC+]; τοῦτο ἤδη -ώτερον harder, more difficult, [Refs 5th c.BC+]
__4 of language, τὸ εὔτονον καὶ σ. solidity, [Refs 1st c.BC+]
__5 σ. ζῴδια, i.e. productive of settled conditions, [Refs 2nd c.BC+]
__II of bodies and quantities, solid, cubic, opposed to ἐπίπεδος (plane), [Refs 5th c.BC+]; σ. γωνία a solid angle, [Refs 3rd c.BC+]; σ. ἀριθμός a cubic number, [Refs 4th c.BC+]; τὰ σ. cubic numbers, representing bodies of three dimensions, [Refs 5th c.BC+]: dative singular στερεῷ in the third power, [Refs]. (Cf. Sanskrit sthirás 'firm, hard, solid', OHG. star 'rigid', O[Refs 5th c.BC+] starian 'stare fixedly'.)

_{LSJ Scripture Refs: Heb.5.12}