Sentence:  Let bears and lions <WSD>growl</WSD> and fight, / Let bears and lions <WSD>growl</WSD> and fight, / For 'tis their nature too, / For 'tis their nature too. 
Meaning of the word marked with <WSD> tags:  To utter a deep guttural sound, as an angry animal; to give forth an angry, grumbling sound.