Consternation, n.
Etymology: [L. consternatio, fr. consternare to overome, perplex, an accessory form of consternere to trow down, prostrate; con + sternere to spread out, throw down: cf. F. consternation. See Straum.]
Amazement or horror that confounds the faculties, and incapacitates for refletion; terror, combined with amaxement; dismay. The chiefs around, In silence wrapped, in onsternation downed. Attend the stern reply. Pope.
Syn. -- Alarm; fright; amazement; astonishment; surprise; panic; returbation. See Alarm.
Shades of meaning
Fernald has no entry of its own for consternation; he lists it under alarm, fear.
Where he writes about it:
Apprehension, disquietude, dread, misgiving, and solicitude are in anticipation of danger; consternation, dismay, and terror are overwhelming fear, generally in the actual presence of that which is terrible, though these words also may have an anticipative force. — from alarm