The suffix “-logy” is used to designate an area of interest or study — such as psychology (the study of the mind) or horology (both the study of time and the art of making clocks). However, the word “logy” is completely distinct, albeit spelled the same. “Logy” — a synonym for “sluggish” — is an American English word that can’t be traced to another root language directly, but some lexicographers have pointed out a resemblance to the Dutch word “log,” which means “heavy, dull.” The “-logy” combining form is much more commonly used, and it has a clear path to the Latin suffix “-logia,” which came from the Greek word “logos,” meaning “word.”