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.
Definition of ascender. 1  1 : the part of a lowercase letter (such as b) that rises above the main body of the letter; also : a letter that has such a part. 2  2 : a device used for climbing rope that slides freely in one direction and grips the rope when pulled in the opposite direction.