imperceptible, unperceivable
(adjective) impossible or difficult to perceive by the mind or senses; “an imperceptible drop in temperature”; “an imperceptible nod”; “color is unperceivable to the touch”
Source: WordNet® 3.1
imperceptible (comparative more imperceptible, superlative most imperceptible)
not perceptible, not detectable, too small in magnitude to be observed
Synonyms: imperceivable, undistinguishable, unperceivable
Antonyms: detectable, perceptible
Source: Wiktionary
Im`per*cep"ti*ble, a. Etym: [Pref. im- not + perceptible: cf. F. imperceptible.]
Definition: Not perceptible; not to be apprehended or cognized by the souses; not discernible by the mind; not easily apprehended. Almost imperceptible to the touch. Dryden. Its operation is slow, and in some cases almost imperceptible. Burke.
– Im`per*cep"ti*ble*ness, n.
– Im`per*cep"ti*bly, adv. Their . . . subility and imperceptibleness. Sir M. Hale.
Source: Webster’s Unabridged Dictionary 1913 Edition
2 April 2025
(adjective) secret or hidden; not openly practiced or engaged in or shown or avowed; “covert actions by the CIA”; “covert funding for the rebels”
The first coffee-house in Mecca dates back to the 1510s. The beverage was in Turkey by the 1530s. It appeared in Europe circa 1515-1519 and was introduced to England by 1650. By 1675 the country had more than 3,000 coffee houses, and coffee had replaced beer as a breakfast drink.
