1. That can be accomplished with little effort. Now with somewhat disparaging sense. Formerly used as predicate with inf. phrase as subject, and in phrase facile and easy.
2. A. Of a course of action, a method: Presenting few difficulties. B. Easy to understand or to make use of.
3. Moving without effort, unconstrained; flowing, running, or working freely; fluent, ready.
4. Of persons, dispositions, speech, etc. A. Easy of access or converse, affable, courteous. B. Characterized by ease of behaviour. C. Not harsh or severe, gentle, lenient, mild.
5. Easily led or wrought upon; flexible, pliant; compliant, yielding.
6. A. quasi-adv. Easily; without difficulty. B. in Scots Law. ‘Possessing that softness of disposition that he is liable to be easily wrought upon by others C. Of things: Easily moved, yielding, ‘easily surmountable; easily conquerable.
(OED, 2nd Ed, accessed through U of MN Libraries)
Taubes: “…an explanation for leanness that the British metabolism researchers Nancy Rothwell and Michael Stock described in 1981 as ‘facile and unlikely,’ a kind way of putting it” (248).
Sentence: The mayor claimed that all the city’s crime was caused by criminals, a conclusion that critics derided as being facile.