According to Hanks & Hodges, Disney is an anglicized (Norman) habitation name, "with fused preposition *de*, from *Isigny* in Calvados, so called from the Gallo-Roman personal name *Isinius* (a Latinized form of Gaulish *Isina*) + the local suffix *-acum*."
In plain English, "Disney" means "from the French town of Isigny-sur-Mer", which also happens to have been Walt Disney's ancestral home --
"D'Isigny" having been the original form of his family's name back in medieval times.
-- Nanaea