The term major-orders can be replaced by several synonyms depending on the context in which it's being used. One option is "main categories", which refers to the top-level classification of subjects or items in a list. Another alternative is "primary divisions", which indicates the primary subdivisions of a larger group or set. Alternatively, "major headings" can be used to describe the most significant sections or subsections of a document or report. Other possible synonyms for major-orders include "key segments", "dominant classes", "pivotal classes", or "critical categories". The choice of synonym depends on the intended meaning and the context in which it's used.