Crabs and their close relatives have 10 legs, arranged in five pairs. Some of their legs are used for walking, while others are used for swimming or defense.
Definition of plunge for English Language Learners. : 1  a sudden fall or jump usually from a high place. : 2  a sudden quick fall in amount, value, etc. : 3  the act of suddenly beginning to be in a particular condition or situation.
1. descend-move downward and lower, but not necessarily all the way; The temperature is going down; The barometer is falling; The curtain fell on the diva; Her hand went up and then fell again. come down, go down, fall. prolapse-slip or fall out of place, as of body parts; prolapsed rectum.