cubit

noun3

1. •
   The distance from the elbow to the tip of the middle finger used as an informal unit of length.

   • Which of you by taking thought can add one cubit unto his stature? — 1611
2. •
   (historical) Any of various units of length approximating this distance, usually around 35–60 cm.
3. •
   (no longer used) Synonym of ulna, the bone of the human forearm.