1.Definition: barely able to be perceived

"An almost insensible change"

Related Adjective(s):indiscernible, undetectable

2.Definition: incapable of physical sensation

"Insensible to pain", "Insensible earth"

3.Definition: unaware of or indifferent to

"Insensible to the suffering around him"

Related Adjective(s):unaffected

4.Definition: unresponsive to stimulation

"He lay insensible where he had fallen"

Related Adjective(s):senseless