Something that's pendular swings back and forth as it's dangled from above. A hypnotist in an old movie will inevitably mesmerize his patient by holding a pendular pocket watch and saying, "You're getting very sleepy."
Pendular things resemble a pendulum, a word from the Latin pendere, "to hang." The classic example is a clock counting the seconds with pendular movements, like a black cat clock with moving eyeballs and a pendular tail that swings back and forth from a fixed point. You can also use this word figuratively for things that move through regular cycles: "Elections tend to be pendular, so the President's party will probably lose in the midterms."