A museme is the smallest unit in any music that has significance or meaning. People often compare it to the morpheme in linguistics, which is a combination of sounds that have meaning. In theory, all music is made up of complex strings and stacks of musemes.
People generally credit Charles Seegar with coming up with the term "museme." In attempting to define the concept of the smallest musical unit of meaning, he combined the beginning of "music" with the end of "morpheme." Later, Bill Brooks suggested the museme string, or sequence of musemes. He also suggested the museme stack, which is simply different musemes occurring simultaneously. This accommodates the fact that music often has multiple individual parts that compliment and play off of each other.
Even though the musical museme has been seen as analogous to the language morpheme, defining a museme in this way creates a major problem, as noted by Philip Tagg: Culture is necessary to provide meaning to anything. In this context, different people can interpret the same minimal musical unit to mean different things. In fact, this is the basis of musical interpretation and which makes the same composition performed by two different players or singers so drastically distinguishable. This means it is impossible to define exactly what a museme means, even when the museme itself is identifiable.
Understanding that the meaning behind a museme is somewhat ambiguous, musicologists have to be flexible in setting standards for what actually makes up an individual meaningful musical unit, as well. For instance, a dancer might see musemes as individual beats, because individual beats often correspond to steps the dancer is supposed to take. For a jazz musician, a museme could be a particular set of chords around which he must improvise.
In a very broad sense, all music is supposed to engage people's artistic sense. It is supposed to satisfy the emotional and spiritual desires of human beings to some degree, as well. Despite the difficulty in explaining the meaning behind the individual musemes found in a piece of music, musicologists are interested in musemes because it is the way musemes are arranged and work together that determine whether music fulfills these roles. By looking closely at musemes, musicologists are looking for a sort of "code" that can reveal why the music is so powerful or stirring, in much the same way that linguists hope to uncover how individual sounds contribute to sophisticated verbal communication.