The term SYNONYM SOURCE is related to the crossword solutions ROGET (5 letters) and ROGETS (6 letters). Both of these words refer to Peter Mark Roget, an English physician, natural theologian, and lexicographer who is best known for publishing Roget's Thesaurus in 1852. This thesaurus is a collection of related words and phrases that are organized into categories and subcategories. As such, it is a useful source for finding synonyms.