From Longman Dictionary of Contemporary Englishundatedun‧dat‧ed /ʌnˈdeɪtɪd/ adjective a letter, article, painting etc that is undated does not have a date written on it
Examples from the Corpus
undated• There are about 12 records, of which three are undated.• And likewise, finds of that period found in a layer which is otherwise undated can help to date that layer.• The finding of an undated Command Paper may give trouble unless the following table is known.• Elizabeth Jerichau-Baumann's undated painting Odalisque subscribes to the stereotypes of the female nude propagated by her male counterparts.• One is a small pile of undated photographs I have from my early childhood.• Dating Discovering exactly when an undated rug was made is almost impossible.• This latter remains undated, though it was not the earliest feature on site, overlying at least one slot-like channel.• Most of Rodin's drawings are undated, unsigned and untitled, so she had to work virtually from scratch.From Longman Business Dictionaryundatedun‧dat‧ed /ʌnˈdeɪtɪd/ adjective1undated bond/security etcFINANCE a bond etc that has no MATURITY (=date at which it will be repaid). A few British government bonds are undated2undated cheque/documentBANKING an undated cheque etc has no date written on it 