September is Etymology Month (17)

scruple "moral misgiving, pang of conscience," late 14c., from O.Fr. scrupule (14c.), from L. scrupulus "uneasiness, anxiety, pricking of conscience," lit. "small sharp stone," dim. of scrupus "sharp stone or pebble," used figuratively by Cicero for a cause of uneasiness or anxiety, probably from the notion of having a pebble in one's shoe. A more literal Latin sense of "small unit of weight or measurement" is attested in English from late 14c.