What does the word clog mean?

Usage examples for clog

  1. If of a friend, he ceases to be one the moment you feel that you are bound to him by the heavy clog of obligation. – Roughing it in the Bush by Susanna Moodie
  2. I guess I'll announce to them that you will favor them with a song and single clog, and then we will appear together. – Twenty Years of Hus'ling by J. P. Johnston