utmost

When used as an adjective, "utmost" usually comes before a noun (like "importance" or "care") to emphasize that something is at the highest possible level. When used as a noun, it is most commonly seen in the phrase "do one's utmost," which means to try as hard as you possibly can. In this context, it functions similarly to the word "best." This word is generally more formal than words like "most" or "best." You will often see it in professional emails, official documents, or serious speeches.