Thigpen Library provides access to the Oxford English Dictionary (OED), the ultimate English language dictionary. Find it on the Thigpen shelves (PE 1625 .O86 2001) or online in the O section of our A to Z database listing.
Or simply define a word straight from the search bar in an internet search engine. In Google use Def:, followed by the word, ie. Def: simple and in DuckDuckGo use Define.