imperceptible
UK[ˌɪmpəˈseptəbl̩]US[ˌɪmpərˈseptəbl̩]
adj
impossible to see or notice because of being very slight, gradual, or subtle
Morpheme Breakdown
im
percept
ible
im
not
percept
perceive
ible
capable of
Etymology
The word 'imperceptible' is a direct borrowing from Late Latin imperceptibilis. It is constructed from the Latin negative prefix in- (which assimilates to im- before 'p'), the verb percipere (to seize, grasp, perceive), and the adjective-forming suffix -ibilis. The literal Latin construction meant "not capable of being seized or perceived". This logical combination traveled through French into English, retaining its core semantic logic: if something cannot (im-) be grasped by the senses or mind (percept-), it is, by definition, (-ible) unable to be noticed.
Analysis
Structure: im (not) + percept (perceive) + ible (capable of)
im: Latin origin, a prefix meaning "not" or "without".
percept: Derived from Latin perceptus, the past participle of percipere meaning "to seize entirely, to perceive". It functions as the core root.
ible: Latin suffix -ibilis, meaning "capable of, able to be", used to form adjectives.
Examples
The changes in the painting were so subtle as to be imperceptible to the casual observer.
Over the years, the coastline had undergone an imperceptible shift.
There was an almost imperceptible nod of agreement from the silent figure.