The concept of Musaicing stems from transposing the notion of mosaicing (a technique for creating large images by aggregating small ones) in the domain of audio.
Musaicing is indeed a technique for creating (large) sequence of (small) sound samples such that the sequence as a whole satisfies various high-level properties. Techniques of constraint solving are used to identify and order the samples (the right samples at the right time) using high-level properties.