Having no depth, or having a depth that is impossible to determine(adjective)
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Use "depthless" in a sentence
"Appropriately enough, the plate's iconic force -- reminiscent of non-perspectival medieval representations -- grows out of the violent contrast between the "depthless" Gestalt of Los trapped "in dreamless night" and his gaze of catastrophic expectation (reinforced by the toothless, semingly disfigured mouth)."
"His eyes are depthless, empty as a bull terrier's."
"I can see beyond, in my mind's eye, unending spaces, and superhuman silences, and depthless calm, till what I feel is almost fear."