Commemorate :: Commemorate (v. t.) To call to remembrance by a special act or observance; to celebrate with honor and solemnity; to honor, as a person or event, by some act of respect or affection, intended to preserve the remembrance of the person or event; as, to commemorate the sufferings and dying love of our Savior by the sacrament of the Lord's Supper; to commemorate the Declaration of Independence by the observance of the Fourth of July..
Memorandum :: Memorandum (n.) A record of something which it is desired to remember; a note to help the memory.
Memorandum :: Memorandum (n.) A brief or informal note in writing of some transaction, or an outline of an intended instrument; an instrument drawn up in a brief and compendious form..