要紧
yào jǐn · HSK 7
important
⏰ 要 (important) + 紧 (tight/tense) = a matter so important it feels tight and pressing
要 — west 覀 (top) + woman 女 (bottom)
Originally a pictograph of a woman with hands on her waist, meaning 'waist' (the original form of 腰). The top 覀 is a stylized depiction of the waist area, not the character for 'west'. Over time it was borrowed for the meaning 'to want, important', so 腰 (with 月 flesh radical) was created for the original 'waist' sense.
紧 — 臣 minister + 又 hand on top + 糸 silk below
Originally written 緊, this character combines 臤 (a hand 又 grasping firmly, with 臣 as phonetic) over 糸 'silk thread'. The image is of silk threads pulled taut by hand, giving the core meaning 'tight, taut'. From there it extended to 'urgent' and 'pressing'.