macies, -ei, f. thinness, leanness
Declension: Macies is a Latin noun of the fifth declension.
Etymology: An Etymological Dictionary of the Latin Language, by Francis Edward Jackson Valpy (1828), says that the adjectival form of macies, macer, comes from the Greek μακρος (makros), which means long. That macer means nothing like "long," but instead "lean, thin", Valpy explains by saying that something thin appears long and stretched out.
English Derivative: Emaciated and meager (meagre)
Example and Tip:
Pliny's ghost story uses the noun in the form macie. 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. This is not an issue for figuring out which case macie is in.