Devonian

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, relating to, or being the period of geologic time from about 416 to 359 million years ago, the fourth period of the Paleozoic Era. The Devonian Period is characterized by the development of lobe-finned fishes, the appearance of amphibians and insects, and the first forests.
• noun The Devonian Period.

from The Century Dictionary.

• Of or pertaining to Devonshire in England.
• The term was applied specifically, in geology, by Murchison to a great part of the Paleozoic strata of North and South Devon, and used by him as synonymous with Old Red Sandstone, for which term he substituted it, “because the strata of that age in Devonshire—lithologically very unlike the old red sandstone of Scotland, Hereford, and the South Welsh counties—contain a much more copious and rich fossil fauna, and were shown to occupy the same intermediate position between the Silurian and Carboniferous rocks.” Later geologists, however, do not use the terms as identical, the conditions under which the strata were deposited being very different.
• This term was first applied in geology by Sedgwick and Murchison to a series of rocks in North and South Devon and Cornwall in which fossils had been found which were recognized by Lonsdale as intermediate in character between Silurian and Carboniferous. The lower and upper limits of the formation were not defined in Britain, but were more precisely determined by the same geologists in the Rhineland. So uncertain, however, were the bounds assigned to the base of the formation that more recent study in various countries has added to the lower part of this system considerable beds that had before been assigned to the Silurian system. Strictly applied, the term Devonian implies the rocks bearing the marine faunas of that time and is contrasted with the Old Red Sandstone, which is a formation sometimes different lithologically and which represents the lake, lagoon, or delta deposits of the same age.
• noun A native or inhabitant of Devonshire.
• noun In geology, the Devonian series.

from the GNU version of the Collaborative International Dictionary of English.

• noun The Devonian age or formation.
• adjective (Geol.) Of or pertaining to Devon or Devonshire in England.
• adjective (Geol.) the age next older than the Carboniferous and later than the Silurian; -- called also the Age of fishes. The various strata of this age compose the Devonian formation or system, and include the old red sandstone of Great Britain. They contain, besides plants and numerous invertebrates, the bony portions of many large and remarkable fishes of extinct groups. See the Diagram under Geology.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective geology of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 415 to 360 million years ago
• adjective Of or pertaining to the English region of Devon.
• noun A native or inhabitant of the English region of Devon.
• proper noun geology the Devonian period

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun from 405 million to 345 million years ago; preponderance of fishes and appearance of amphibians and ammonites