vinculum, -i, n. chain
In English: A vinculum is horizontal bar notation used in mathematics.
Example and Tip:
Pliny's ghost story uses the noun in the form vinculorum. Determine which case it could be in by running through the paradigm in your mind or by consulting the paradigm below. Note the macrons appear in this paradigm. There are no macrons in Rose William's version of Pliny's haunted house story, but in this case, you should not need to look for other clues to determine which part of speech it is in.