So slight, gradual, or subtle as to be difficult or impossible to perceive or detect. It describes changes or qualities that escape notice.
From Latin 'imperceptibilis,' composed of 'in-' (not) and 'perceptibilis' (able to be perceived), from 'percipere' (to perceive). The word entered English in the 17th century, emphasizing the limits of human perception.
Think 'im-perceptible' - not able to be perceived! This word often appears in science passages about gradual changes, subtle differences, or things at the edge of detection.
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