The word 要紧 is formed by combining two independent characters, each contributing its core meaning to create a new, composite idea. The first character, 要 (yào), carries the sense of "wanting" or, more abstractly, "essential importance". The second, 紧 (jǐn), conveys notions of "tightness", "tension", and "urgency". When fused, their individual concepts interact synergistically: the "essential" nature of 要 is intensified by the "urgent pressure" of 紧, resulting in the combined meaning of something being "critical", "serious", or "of vital importance", where urgency and significance are inextricably linked.