When it comes to describing someone who is ardently serious, there are a wide range of synonyms to choose from. Some alternatives might include somber, resolute, grave, stern, steadfast, determined, intense, passionate, purposeful, or committed. Each of these words conveys a sense of deep seriousness and dedication, suggesting that the individual in question has a strong and unwavering sense of purpose. Other related words might include earnest, fervent, zealous, or dedicated, which likewise suggest a passion and dedication to a particular cause or goal. Whether you are describing someone's character, personality, or actions, choosing the right words can help to convey a powerful message about their level of commitment and seriousness.