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.
take the plunge. Venture something, commit oneself, as in You've been living together for a year, so when are you going to take the plunge and get married? It is also put as make the plunge, plunge alluding to diving in a body of water. [Mid-1800s]