Macs come with a Dictionary app. It’s very handy. Find it in the Applications folder.
When you launch it, you get this (you will, that is, if you type “sleep” into the search box):
EVERY word in the Dictionary is clickable! I mean “every”– and that includes words in the definitions! So try clicking. Also, try the thesaurus and the Apple and Wikipedia sections.
Want some more, longer how-tos?
Visit my other website, christianboyce.com