- 어마어마하다 = enormous, gargantuan (extreme in size or scale, or quantity sometimes). - 굉장하다 = remarkable or spectacular in appearance, degree, etc. - 엄청나다 = overwhelming in scale or quantity, tremendous in impact, etc. - 굉장히 크다 = remarkably large. - 거대하다 = (about the same as 굉장히 크다, except that it's single adjective) - 대단하다 = amazing or impressive (usually about positive things like an ability, achievement, etc) 어마어마하다, 굉장히 크다, and 거대하다 are primarily about physical size or scale. 굉장하다 and 엄청나다 apply more broadly to both physical scale and abstract things like efforts or determination. 대단하다 is not so much about scale as some remarkable quality, as in 그 사람은 참 대단해 (He is just amazing). Most of these words already have the sense of something extreme, so you usually don't need another adverb to intensify them. Some adverb + adjective combinations would work but not all. For example, 아주/엄청/되게 거대한 몸집 and 아주/참 대단한 능력 sound fine, but 꽤 and 무지 don't go well with most, and 매우 and 되게 would sound odd with some. To describe something as even bigger, one might choose a different expression instead of adding adverbs. For example, you might say 입이 딱 벌어지게 큰 (jaw-droppingly massive), 상상도 못하게 큰 (huge beyond your wildest imagination), etc.