Virile, a.
Etymology: [L. virilis, fr. vir a man; akin to AS. wer: cf. F. viril. See Werewolf, World, and cf. Decemvir, Virago, Virtue.]
Having the nature, properties, or qualities, of an adult man; characteristic of developed manhood; hence, masterful; forceful; specifically, capable of begetting; -- opposed to womanly, feminine, and puerile; as, virile age, virile power, virile organs.
Shades of meaning
Fernald has no entry of its own for virile; he lists it under masculine.
Where he writes about it:
Masculine may apply to the distinctive qualities of the male sex at any age; virile applies to the distinctive qualities of mature manhood only, as opposed not only to feminine or womanly but to childish, and is thus an emphatic word for sturdy, intrepid, etc. — from masculine