Propugn is a rare word that means to defend or advocate for something. If you're looking for synonyms to use instead of "propugn," there are a number of options available to you. For example, you might try using words like argue, support, or champion. These terms all convey the idea of actively advocating for a particular position or stance. Additionally, you could use words like promote, advance, or boost to suggest that you are actively working to help a particular idea or cause gain traction or momentum. Overall, there are many different words you could use to express the idea of "propugning" something, depending on the precise meaning and connotations you're trying to convey.