Definition of aphantasia in US English:

aphantasia

noun

Medicine
  • The inability to form mental images of objects that are not present.

    ‘if counting sheep is an abstract concept, or you are unable to visualize the faces of loved ones, you could have aphantasia’

Origin

Early 21st century: from a- ‘without, not’ + Greek phantasia ‘imagination, appearance’.

Pronunciation

aphantasia

/ˌeɪˌfænˈteɪziə//ˌāˌfanˈtāzēə/