When you espouse an idea, you take it as yours and stand behind it in public — especially a political, moral, or social belief. The word is fairly formal. Newspapers and speeches use it; friends at a night market almost never do. A party may espouse free trade; a writer may espouse a cause. You can espouse something without living it perfectly every day: the word is about what you claim and support, not a score of your private life. Though actually, it began as a marriage word. To espouse someone was to take them as a husband or wife. That older sense is rare now, and it can sound dated or legal, but it still sits under the modern one — you are, in a way, marrying the idea.