Definition of pregeological in US English:

pregeological

adjective

Geology
  • Designating, relating to, or occurring in the time before that studied by geology, or earlier than the time of formation of the oldest known rocks (now reckoned as about 4000 million years ago).

Origin

Mid 19th century; earliest use found in Thomas Huxley (1825–1895), biologist and science educationist. From pre- + geological.

Pronunciation

pregeological

/ˌpriːdʒiːəˈlɒdʒɪkl/