The Collaborative International Dictionary of English v.0.48:

Memorial \Me*mo"ri*al\, a. [F. m['e]morial, L. memorialis, fr.
   memoria. See Memory.]
   [1913 Webster]
   1. Serving to preserve remembrance; commemorative; as, a
      memorial building.
      [1913 Webster]

            There high in air, memorial of my name,
            Fix the smooth oar, and bid me live to fame. --Pope.
      [1913 Webster]

   2. Contained in memory; as, a memorial possession.
      [1913 Webster]

   3. Mnemonic; assisting the memory.
      [1913 Webster]

            This succession of Aspirate, Soft, and Hard, may be
            expressed by the memorial word ASH.   --Skeat.
      [1913 Webster]

   Memorial Day. See Memorial Day in the vocabulary. Also
      called Decoration Day. [U.S.]
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Memorial \Me*mo"ri*al\, n. [Cf. F. m['e]morial.]
   1. Anything intended to preserve the memory of a person or
      event; something which serves to keep something else in
      remembrance; a monument. --Macaulay.
      [1913 Webster]

            Churches have names; some as memorials of peace,
            some of wisdom, some in memory of the Trinity
            itself.                               --Hooker.
      [1913 Webster]

   2. A memorandum; a record. [Obs. or R.] --Hayward.
      [1913 Webster]

   3. A written representation of facts, addressed to the
      government, or to some branch of it, or to a society,
      etc., -- often accompanied with a petition.
      [1913 Webster]

   4. Memory; remembrance. [Obs.]
      [1913 Webster]

            Precious is the memorial of the just. --Evelyn.
      [1913 Webster]

   5. (Diplomacy) A species of informal state paper, much used
      in negotiation.
      [1913 Webster]

WordNet (r) 3.0 (2006):

memorial
    n 1: a recognition of meritorious service [syn: memorial,
         commemoration, remembrance]
    2: a written statement of facts submitted in conjunction with a
       petition to an authority
    3: a structure erected to commemorate persons or events [syn:
       memorial, monument]

Moby Thesaurus II by Grady Ward, 1.0:

143 Moby Thesaurus words for "memorial":
   Clio, Muse of history, account, adventures, adversaria,
   aide-memoire, annals, annotation, arch, autobiography, barrow,
   biographical sketch, biography, boundary stone, brass, bust, cairn,
   case history, catalog, celebrating, celebrative, cenotaph,
   chronicle, chronicles, chronology, column, commemorating,
   commemoration, commemorative, confessions, correspondence,
   cromlech, cross, cup, curriculum vitae, cyclolith, diary, docket,
   documentation, dolmen, entry, experiences, favor, footnote,
   footstone, fortunes, grave, gravestone, hagiography, hagiology,
   headstone, historiography, history, hoarstone, inscription,
   inventory, item, jotting, journal, keepsake, legend, letters, life,
   life and letters, life story, list, marginal note, marginalia,
   marker, martyrology, mausoleum, megalith, memento, memento mori,
   memo, memoir, memoirs, memorabilia, memorandum, memorial arch,
   memorial column, memorial statue, memorial stone, memorials,
   memories, menhir, minutes, monolith, monument, mound, necrology,
   notation, note, obelisk, obituary, photobiography, pillar,
   pipe roll, plaque, prize, profile, pyramid, record, recording,
   register, registry, relic, reliquary, remains, remembrance,
   remembrancer, reminder, resume, ribbon, roll, rolls, roster,
   rostral column, rota, scholia, scholium, scroll, shaft, shrine,
   solemn, souvenir, statue, stela, stone, story, stupa, table,
   tablet, testimonial, theory of history, token,
   token of remembrance, tomb, tombstone, tope, trace, trophy,
   vestige