Sentence:  Clojure uses the Boolean operators "or" and "and". "or" returns either the first <WSD>truthy</WSD> value or the last value, "and" returns the first falsey value or, if no values are falsey, the last <WSD>truthy</WSD> value. 
Meaning of the word marked with <WSD> tags:  Evaluating to true in a Boolean context.