This is just a question about terminology that is used in the beginning of a chapter about phonons.
In a simple cubic crystal, we can consider elastic oscillations in f.i. the [100] direction. In this direction there is one longitudinal and two transversal oscillation modes. Now my textbook tells that these two transversal oscillation modes can be degenerate. I wonder in which sense the word "degenerate" is used here and I hope that someone can clarify this.