Scrupulum
Scrupulum, meaning a tiny stone (from scrupus sharp stone), indicates a weight of 1/24 of an ounce or, by extension, of other measures. Metaphorically, the stone is thought to be sharp and pricking, like a thorn. As a weight or a coin, 1/24 of an uncia, or 1/288 of an as As a measure of land, 1/288 of a jugerum As a measure of time, 1/24 part of an hour. The forms scripulum, scriptulum, scriplus and scriptulus can be found, scriptulum being also associated with the lines on a draughtboard.
en.wikipedia.org