He stood up, making an excuse, imperceptibility lurching as he did so.
Ninety-nine hundredths of this amiable world of ours would have guffawed the poor creature into imperceptibility ages ago.
1670s, from imperceptible + -ity.
early 15c., from French imperceptible (early 15c.), from Medieval Latin imperceptibilis, from assimilated form of in- "not, opposite of" (see in- (1)) + perceptibilis (see perceptible). Related: Imperceptibly. OED marks imperceivable as "Now rare."