Frank J. Wilstach, comp. A Dictionary of Similes. 1916.

Vague

Vague as a shadow.
—Anonymous

Vague like a suggestion of solid darkness.
—Joseph Conrad

Vague … like feathers wafted backwards
From passage birds in flight.
—William Dean Howells

Vague and unmarked as desert sands.
—Mary Johnston

Vague as solitary dove,
Nor knew that nests were built.
—John Keats

Vague, like the thoughts of a child.
—Charles Kingsley

A vague presentment of impending doom,
Like ghostly footsteps in a vacant room.
—Henry W. Longfellow

Vague surmise
Shines in the father’s gentle eyes,
As firelight on a window-pane
Glimmers and vanishes away.
—Henry W. Longfellow

Vague as futurity.
—Owen Meredith

Vague as the music of a moon-bathed brook.
—Francis S. Saltus