Insensibility, n.
Etymology: [Cf. F. insensibilité.]
1. The state or quality of being insensible; want of sensibility; torpor; unconsciousness; as, the insensibility produced by a fall, or by opiates.
2. Want of tenderness or susceptibility of emotion or passion; dullness; stupidity.
Syn. -- Dullness; numbness; unfeelingness; stupidity; torpor; apathy; impassiveness; indifference.
Shades of meaning
Fernald has no entry of its own for insensibility; he lists it under apathy, stupidity, stupor.
Where he writes about it:
Indifference and insensibility designate the absence of feeling toward certain persons or things; apathy, entire absence of feeling. — from apathy
Indifference is a want of interest; insensibility is a want of feeling; unconcern has reference to consequences. — from apathy
We speak of insensibility of heart, immobility of countenance. — from apathy
Coma is a deep, abnormal sleep, from which the patient can not be aroused, or is aroused only with difficulty, a state of profound insensibility, perhaps with full pulse and deep, stertorous breathing, and is due to brain-oppression. — from stupor
Insensibility is a general term denoting loss of feeling from any cause, as from cold, intoxication, or injury. — from stupor
Stupor is especially profound and confirmed insensibility, properly comatose. — from stupor