Definition of "featureless"

This one was almost featureless, as if still in the making, with an aspect of monotonous grimness.

1899 February, Joseph Conrad, “The Heart of Darkness”, in Blackwood’s Edinburgh Magazine, volume CLXV, number M, New York, N.Y.: The Leonard Scott Publishing Company, […], part I, page 202

The branch is three and a half miles long over virtually level, featureless countryside.

1961 May, Mark B. Warburton, “Yatton and its branches to Clevedon and Wells”, in Trains Illustrated, page 278