契机
qìjī · HSK 7
turning point
🔑 契 pact + 机 opportunity/juncture = the deciding moment that turns things
机 is the same 机 in 飞机 (machine), but here it carries its other sense: opportunity or juncture. Paired with 契 (pact, agreement), 契机 names the agreed-on hinge point that sets a change in motion.