Source : Webster's Revised Unabridged Dictionary (1913)

Rhaetic \Rh[ae]"tic\, a. [L. Rhaeticus Rhetain.] (Geol.)
   Pertining to, or of the same horizon as, certain Mesozoic
   strata of the Rhetain Alps. These strata are regarded as
   closing the Triassic period. See the Chart of {Geology}.