The term "sub-fix" is commonly used to refer to a morpheme that is added to the beginning of a root or base word in order to create a new word. Some synonyms for this term that can be used interchangeably in certain contexts include prefixes, pre-fixes, and affixes. These terms refer to similar components of word formation and can be used to describe the same concepts in various linguistic contexts. Whether you're discussing language morphology or simply examining word formation in different languages, these terms can help you to understand the complex interplay between language and communication.