Summary: Prefixes are key morphemes in English vocabulary that begin words. The English prefix *de-*, which means "off" or "from," appears in hundreds of English vocabulary words, such as [*de*]jected, [*de*]duce, and [*de*]ficient. You can remember that the prefix *de-* means "from" or "off" via the word [*de*]scend, or to climb down "from" or "off" a height, such as a mountain.
