Formidable : inspiring fear or respect through being impressively large, powerful, intense, or capable.Bitter : having a sharp, pungent taste or smell; not sweet.Pregnant : (of a woman or female animal) having a child or young developing in the uterus.Solemn : not cheerful or smiling; serious.Grave : serious or solemn in manner or appearance.Synonym of Grave is Solemn