Mailer defined it as "the emotional promiscuity of those who have no sentiments". Another definition occurred to me recently. A poem can be considered "sentimental" if it aims to make the reader feel something in particular, rather than make the reader feel more precisely. This can happen either because the poet is too aware of himself or because he is too aware of his reader. The first kind of sentimentality often consists of an attempt to make the reader (whoever she is) pity the poet. The second kind often consist of some more or less overt attempt to arouse the reader (who is the object of his affection). But there are all kinds of less "personal" forms of sentimentality (the poet may want to make the reader feel sympathy for a class of victims or may want the reader to admire his taste in music). We can often rid a poem of sentimentality by removing references to things or events that both the poet and the reader are presumably familiar with. Or by converting them into images that no longer presume such familiarity.