This paper presents Query-by-Blending, a novel music exploration system that enables users to find unfamiliar music content by flexibly combining three musical aspects: lyric word, song audio, and artist. Although there are various systems for music retrieval based on the similarity between songs or artists and for music browsing based on visualized songs, it is still difficult to explore unfamiliar content by flexibly combining multiple musical aspects. Query-by-Blending overcomes this difficulty by representing each of the aspects as a latent vector representation (called a "flavor" in this paper) that is a distinctive quality felt to be characteristic of a given word/song/artist. By giving a lyric word as a query, for example, a user can find songs and artists whose flavors are similar to the flavor of the query word. Moreover, by giving a query combining (blending) lyric-word and song-audio flavors, the user can interactively explore unfamiliar content containing the blended flavor. This multi-aspect blending was achieved by constructing a novel vector space model into which all of the lyric words, song audio tracks, and artist IDs of a collection can be embedded. In our experiments, we embedded 14,505 lyric words, 433,936 songs, and 44,696 artists into the same shared vector space and found that the system can appropriately calculate similarities between different aspects and blend flavors to find related lyric words, songs, and artists.