Adjective
Thin; not dense or gross; rare; as, subtile air; subtile vapor; a subtile medium.
Delicately constituted or constructed; nice; fine; delicate; tenuous; finely woven.
Acute; piercing; searching.
Characterized by nicety of discrimination; discerning; delicate; refined; subtle.
Sly; artful; cunning; crafty; subtle; as, a subtile person; a subtile adversary; a subtile scheme.
Source: Webster's dictionaryWhat things have we seen Done at the Mermaid! heard words that have been So nimble and so full of subtile flame As if that every one from whence they came Had meant to put his whole wit in a jest, And resolved to live a fool the rest Of his dull life. Francis Beaumont
As the British Constitution is the most subtile organism which has proceeded from the womb and the long gestation of progressive history, so the American Constitution is, so far as I can see, the most wonderful work ever struck off by the brain and purpose of man. William Ewart Gladstone
Dark Angel, with thine aching lust To rid the world of penitence: Malicious Angel, who still dost My soul such subtile violence! Lionel Johnson