This is an entry in our Disneyland 101 Glossary: Disneyland Resort definitions in under 101 words, from Mouse Brief.
“Split-stay” is a term some guests use to describe staying at more than one hotel over the course of a Disneyland vacation. An example of a split stay would be a one week vacation where you stayed at Pixar Place Hotel for Sunday through Wednesday night and then moved over to Disneyland Hotel for Thursday through Saturday night. A split stay can involve all Disneyland Resort Hotels, all off-site hotels (like Good Neighbor Hotels) or Disneyland Resort hotels and off-site hotels. You may want to consider a split stay in order to experience more hotels or save money.
We have a comparison chart of the Disneyland Resort Hotels here, advice for how to choose one here and for how to make the most of your stay here.