INDISCERNIBLE
indiscernible
(adjective) difficult or impossible to perceive or discern; “an indiscernible increase in temperature”
indiscernible, insensible, undetectable
(adjective) barely able to be perceived; “the transition was almost indiscernible”; “an almost insensible change”
Source: WordNet® 3.1
Etymology
Adjective
indiscernible (comparative more indiscernible, superlative most indiscernible)
Not capable of being discerned, of being perceived.
Not capable of being distinguished from something else.
Noun
indiscernible (plural indiscernibles)
(chiefly, philosophy) Something which is incapable of being discerned.
Source: Wiktionary
In`dis*cern"i*ble, a. Etym: [Pref. in- not + discernible: cf. F.
indiscernable.]
Definition: Not to be discerned; imperceptible; not discoverable or
visible.
Secret and indiscernible ways. Jer. Taylor.
– In`dis*cern"i*ble*ness, n.
– In`dis*cern"i*bly, adv.
Source: Webster’s Unabridged Dictionary 1913 Edition