급감rapid decrease; sharp fall; nosedive 급증rapid increase 급행열차express train 긴급emergency 긴급회의emergency meeting 응급실ER; emergency room 초특급being very speedy 특급special express 화급urgency; emergency 구급relief; rescue

속도speed 고속high speed 과속speeding 속도위반speeding violation 초고속superhigh speed; ultrafast speed 초속speed per second 쾌속high speed 쾌속선fast boat; high-speed boat 쾌속정fast boat; high-speed boat 풍속wind velocity