As wind causes wild waves to stir up dirty foam—so these men, through their false teaching and actions, shame themselves. Alternate translation: "and just as waves bring up foam and dirt, these men pollute others with their shame" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Those who studied the stars in ancient times noticed that some "stars,"—what we call planets—do not move the way that stars do, so they called them "wandering stars." Alternate translation: "They are like moving stars" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Here "darkness" is a metonym that represents the place of the dead or hell, and "the gloom of complete darkness" is an idiom that means "a totally dark place." The phrase "has been reserved" can be stated in active form. Alternate translation: "and God will put them in the gloom and complete darkness of hell forever" (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-idiom]] and [[rc://en/ta/man/jit/figs-activepassive]])