This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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adj. Not measured or sounded with a plumb: unplumbed ocean depths.

adj. Not fully examined or explored: unplumbed ideas.

adj. Not measured for depth, as if with a plumb.

Not plumbed or measured by a plumb-line; unfathomed.

adj. situated at or extending to great depth; too deep to have been sounded or plumbed

"Joyce intended something "unplumbed," as was much of the undulating Sunda (no "m") in 1904, during which Ulysses takes place, two years before soundings by the German vessel Planet."

deep   

red-streaked    unfathomed    traurig    much-neglected    stone-like    unconceived    Epsom    headwater    well-satisfied    star-bespangled