Definition of sub-Aftonian in US English:

sub-Aftonian

adjective

Geology
rare, disused
  • Designating (deposits associated with) a glaciation immediately preceding the Aftonian interglacial in North America; = "Nebraskan".

Origin

Late 19th century; earliest use found in Journal of Geology. From sub- + Aftonian.

Pronunciation

sub-Aftonian

/sʌbafˈtəʊnɪən/