ERD

from The Collaborative International Dictionary of English v.0.48

Erd \Erd\ ([~e]rd), n. [OE. erd, eard, earth, land, country, AS.
   eard; akin to OS. ard dwelling place, OHG. art plowing,
   tillage, Icel. ["o]r[eth] crop, and to L. arare to plow, E.
   ear to plow.]
   The earth. [Prov. Eng.] --Wright.
   [1913 Webster]

   {Erd shrew} (Zo["o]l.), the common European shrew ({Sorex
      vulgaris}); the shrewmouse.
      [1913 Webster]

from The Free On-line Dictionary of Computing (8 July 2008)

entity-relationship model
entity-relationship diagram
ERD

   <database, specification> An approach to {data modelling}
   proposed by P. Chen in 1976.  The model says that you divide
   your database in two logical parts, entities (e.g. "customer",
   "product") and relations ("buys", "pays for").

   Entity-relationship diagrams can be used to represent a model.

   ["The entity-relationship model: toward a unified view of
   data", P.P. Chen, ACM Transactions on Database Systems 1:1 pp
   9-36, 1976].

   (1998-03-20)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

ERD
       Entity-Relationship Diagram