From The Collaborative International Dictionary of English v.0.48 [gcide]:
Insensible \In*sen"si*ble\, a. [L. insensibilis: cf. F.
insensible. See In- not, and Sensible.]
[1913 Webster]
1. Destitute of the power of feeling or perceiving; wanting
bodily sensibility; unconscious. --Milton.
[1913 Webster]
2. Not susceptible of emotion or passion; void of feeling;
apathetic; unconcerned; indifferent; as, insensible to
danger, fear, love, etc.; -- often used with of or to.
[1913 Webster]
Accept an obligation without being a slave to the
giver, or insensible to his kindness. --Sir H.
Wotton.
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Lost in their loves, insensible of shame. --Dryden.
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3. Incapable of being perceived by the senses; imperceptible.
Hence: Progressing by imperceptible degrees; slow;
gradual; as, insensible motion.
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Two small and almost insensible pricks were found
upon Cleopatra's arm. --Sir T.
Browne.
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They fall away,
And languish with insensible decay. --Dryden.
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4. Not sensible or reasonable; meaningless. [Obs.]
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If it make the indictment be insensible or
uncertain, it shall be quashed. --Sir M. Hale.
5. Incapable of feeling a specific sensation or emotion; as,
insensible to pity.
[PJC]
Syn: Imperceptible; imperceivable; dull; stupid; torpid;
numb; unfeeling; apathetic; stoical; impassive;
indifferent; unsusceptible; hard; callous.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
insensible
adj 1: incapable of physical sensation; "insensible to pain";
"insensible earth" [ant: sensible, sensitive]
2: unaware of or indifferent to; "insensible to the suffering
around him" [syn: {insensible(p)}, {unaffected(p)}]
3: barely able to be perceived; "the transition was almost
indiscernible"; "an almost insensible change" [syn:
indiscernible, insensible, undetectable]
4: unresponsive to stimulation; "he lay insensible where he had
fallen"; "drugged and senseless" [syn: insensible,
senseless]