adj.1 a without one's mental faculties; unconscious. b (of the extremities etc.) numb; without feeling.
2 (usu. foll. by of, to) unaware; indifferent (insensible of her needs).
3 without emotion; callous.
4 too small or gradual to be perceived; inappreciable.
Derivatives:
insensibly adv.
Etymology: ME f. OF insensible or L insensibilis (as IN-(1), SENSIBLE)