Im`per*cep"ti*ble (?), a. [Pref. im-
not + perceptible: cf. F. imperceptible.] Not
perceptible; not to be apprehended or cognized by the senses; not
discernible by the mind; not easily apprehended.
Almost imperceptible to the touch.
Dryden.
Its operation is slow, and in some cases almost
imperceptible.
Burke.
-- Im`per*cep"ti*ble*ness, n. --
Im`per*cep"ti*bly, adv.
Their . . . subtilty and
imperceptibleness.
Sir M. Hale.