The definition of art is controversial in contemporary philosophy. Whether art can be defined has also been a matter of controversy. The philosophical usefulness of a definition of art has also been debated. -/- Contemporary definitions can be classified with respect to the dimensions of art they emphasize. One distinctively modern, conventionalist, sort of definition focuses on art’s institutional features, emphasizing the way art changes over time, modern works that appear to break radically with all traditional art, the relational properties (...) of artworks that depend on works’ relations to art history, art genres, etc. – more broadly, on the undeniable heterogeneity of the class of artworks. The more traditional, less conventionalist sort of definition defended in contemporary philosophy makes use of a broader, more traditional concept of aesthetic properties that includes more than art-relational ones, and puts more emphasis on art’s pan-cultural and trans-historical characteristics – in sum, on commonalities across the class of artworks. Hybrid definitions aim to do justice to both the traditional aesthetic dimension as well as to the institutional and art-historical dimensions of art, while privileging neither. (shrink)