— imperceptibility, imperceptibleness , n. — imperceptibly , adv.
/im'peuhr sep"teuh beuhl/ , adj.
1. very slight, gradual, or subtle: the imperceptible slope of the road.
2. not perceptible; not perceived by or affecting the senses.
n.
3. something not capable of being perceived by the senses: metaphysical speculation about imperceptibles.
[ 1520-30; imperceptibilis. See IM- 2 , PERCEPTIBLE ]
Syn. 2. hidden, unperceivable, undetectable.