WordNet (r) 3.0 (2006):

Chaldea
    n 1: an ancient region of Mesopotamia lying between the
         Euphrates delta and the Persian Gulf and the Arabian
         Desert; settled in 1000 BC and destroyed by the Persians in
         539 BC; reached the height of its power under
         Nebuchadnezzar II [syn: Chaldea, Chaldaea]
    2: an ancient kingdom in southern Mesopotamia; Babylonia
       conquered Israel in the 6th century BC and exiled the Jews to
       Babylon (where Daniel became a counselor to the king) [syn:
       Babylonia, Chaldaea, Chaldea]

Easton's 1897 Bible Dictionary:

Chaldea
   The southern portion of Babylonia, Lower Mesopotamia, lying
   chiefly on the right bank of the Euphrates, but commonly used of
   the whole of the Mesopotamian plain. The Hebrew name is Kasdim,
   which is usually rendered "Chaldeans" (Jer. 50:10; 51:24,35).

     The country so named is a vast plain formed by the deposits of
   the Euphrates and the Tigris, extending to about 400 miles along
   the course of these rivers, and about 100 miles in average
   breadth. "In former days the vast plains of Babylon were
   nourished by a complicated system of canals and water-courses,
   which spread over the surface of the country like a network. The
   wants of a teeming population were supplied by a rich soil, not
   less bountiful than that on the banks of the Egyptian Nile. Like
   islands rising from a golden sea of waving corn stood frequent
   groves of palm-trees and pleasant gardens, affording to the
   idler or traveller their grateful and highly-valued shade.
   Crowds of passengers hurried along the dusty roads to and from
   the busy city. The land was rich in corn and wine."

     Recent discoveries, more especially in Babylonia, have thrown
   much light on the history of the Hebrew patriarchs, and have
   illustrated or confirmed the Biblical narrative in many points.
   The ancestor of the Hebrew people, Abram, was, we are told, born
   at "Ur of the Chaldees." "Chaldees" is a mistranslation of the
   Hebrew _Kasdim_, Kasdim being the Old Testament name of the
   Babylonians, while the Chaldees were a tribe who lived on the
   shores of the Persian Gulf, and did not become a part of the
   Babylonian population till the time of Hezekiah. Ur was one of
   the oldest and most famous of the Babylonian cities. Its site is
   now called Mugheir, or Mugayyar, on the western bank of the
   Euphrates, in Southern Babylonia. About a century before the
   birth of Abram it was ruled by a powerful dynasty of kings.
   Their conquests extended to Elam on the one side, and to the
   Lebanon on the other. They were followed by a dynasty of princes
   whose capital was Babylon, and who seem to have been of South
   Arabian origin. The founder of the dynasty was Sumu-abi ("Shem
   is my father"). But soon afterwards Babylonia fell under Elamite
   dominion. The kings of Babylon were compelled to acknowledge the
   supremacy of Elam, and a rival kingdom to that of Babylon, and
   governed by Elamites, sprang up at Larsa, not far from Ur, but
   on the opposite bank of the river. In the time of Abram the king
   of Larsa was Eri-Aku, the son of an Elamite prince, and Eri-Aku,
   as has long been recognized, is the Biblical "Arioch king of
   Ellasar" (Gen. 14:1). The contemporaneous king of Babylon in the
   north, in the country termed Shinar in Scripture, was
   Khammu-rabi. (See BABYLON; ABRAHAM; AMRAPHEL.)


Hitchcock's Bible Names Dictionary (late 1800's):

Chaldea, as demons, or as robbers