rap·id 
/ˈræpəd/ adjective
/ˈræpəd/ adjective [more rapid; most rapid] 1 : happening in a short amount of time : happening quickly
▪ a rapid [=quick] change in temperature ▪ There's been rapid growth in the number of new businesses in the town. ▪ Scientists are concerned about the rapid disappearance of the island's coral reefs. 2 : having a fast rate
▪ a rapid heartbeat ▪ rapid breathing 3 : moving quickly
▪ She carefully guided the boat through the rapid water.
▪ a rapid [=quick] change in temperature ▪ There's been rapid growth in the number of new businesses in the town. ▪ Scientists are concerned about the rapid disappearance of the island's coral reefs.
▪ a rapid heartbeat ▪ rapid breathing
▪ She carefully guided the boat through the rapid water.
— ra·pid·i·ty /rəˈpɪdəti/ noun [noncount]
▪ Doctors were amazed by the rapidity [=speed] of his recovery.
/rəˈpɪdəti/ noun [noncount] ▪ Doctors were amazed by the rapidity [=speed] of his recovery.
— rap·id·ly adverb
▪ the rapidly [=quickly] changing temperature ▪ He was breathing rapidly. ▪ Her heart beat rapidly.
▪ the rapidly [=quickly] changing temperature ▪ He was breathing rapidly. ▪ Her heart beat rapidly.
