Sentence:  A cat is an <WSD>animal</WSD>, not a plant. Humans are also <WSD>animals</WSD>, under the scientific definition, as we are not plants. 
Meaning of the word marked with <WSD> tags:  In (scientific) usage, a multicellular organism that is usually (mobile), whose (cell)s are not encased in a rigid cell wall (distinguishing it from (plants) and (fungi)) and which derives energy solely from the consumption of other organisms (distinguishing it from (plants)).