Slabness

In recent years we have come a long way from the austere slabness of the so-called functional or Bauhaus school and from such blind alleys as Le Corbusier's fancy as a young man that a home should be a "machine to live in."

Source: wiktionary

[…] there was something of youth and eagerness and tension all hidden behind the slabness of his features, the greyness of shape rather than of colour. It was a face so unremarkable in its physical detail that only a couple of small razor nicks stuck in the memory.

Source: wiktionary