'backwardness' definitions:

Definition of 'backwardness'

From: WordNet
noun
Lack of normal development of intellectual capacities [syn: retardation, mental retardation, backwardness, slowness, subnormality]

Definition of 'backwardness'

From: GCIDE
  • backwardness \back"ward*ness\, n. The state of being backward. [1913 Webster]