Coined by T. H. Huxley in 1869 as the opposite of 'Gnostic' — not claiming ignorance, but unknowability.
A person who believes that nothing is known or can be known of the existence of God; relating to the view that the existence of God is unknowable; (by extension) non-committal on a particular topic.
Coined in 1869 by T. H. Huxley from Greek 'a-' (not, without) + 'gnōstikós' (knowing, able to know), from 'gnōstós' (known), from 'gignōskein' (to know, to learn, to perceive), from PIE *ǵneh₃- (to know). Huxley created the word as the deliberate antonym of 'Gnostic' — if Gnostics claimed secret, mystical knowledge of the divine, an agnostic declares that such knowledge is fundamentally unattainable. Huxley described his coinage as expressing 'the exact opposite of the Gnostic,' and the word rapidly entered philosophical and theological
T. H. Huxley coined 'agnostic' in 1869 at a meeting of the Metaphysical Society. He later explained: 'I invented what I conceived to be the appropriate title of agnostic. It came into my head as suggestively antithetic to the Gnostic of Church history, who professed to know so much about the very things of which I was ignorant.' The word spread with extraordinary speed and was in common use within a decade