|any impediment or obstacle|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a scrap or morsel of food left at a meal.|
A hindrance or obstacle, as in His lack of a degree is a real stumbling block to his advancement. This term originally meant "a tree stump over which one trips." Its figurative use dates from the early 1500s.