Originally 止 was a pictographic representation of a foot . For easier writing the five toes were limited to three, and the overall shape restricted to a few lines, making the graph quite abstract (see below). Its current standard form is easy enough to remember as a foot, but hardly looks like one any more.
In composite graphs that date back to oracle bone inscriptions 止 could be used concretely to classify words having to do with the foot, or more abstractly with “moving forward”. When 止 was used on itself in oracle bone inscriptions, 止 could mean “foot” or “to walk, to go”.¹ However, somewhat confusingly later the extended meaning “to stop” came to dominate the use of 止.²