Usage examples for vague:

• Rowland answered her questions; to the last he gave a vague affirmative. "Roderick Hudson" – Henry James

• A dozen vague fears shot through his mind in a moment. "The Squire's Daughter" – Silas K(itto) Hocking

• Something vague moved deep down in the Colonel; he stretched out his hand. "The Dark Flower" – John Galsworthy

• Everything was vague but that something had happened was obvious, and also that that something was pretty serious. "Men, Women and Guns" – H. C. (Herman Cyril) McNeile