'Rhaetic' definitions:
- Rhaetic \Rhae"tic\, a. [L. Rhaeticus Rhetian.] (Geol.)
Pertining to, or of the same horizon as, certain Mesozoic
strata of the Rhetian Alps. These strata are regarded as
closing the Triassic period. See the Chart of Geology.
[1913 Webster]