What is to speak largely or copiously; to be diffuse in argument or description; to dilate; to expatiate; -- often with on or upon. Watts. He must often enlarge and amplify upon the subject he handles. South called?

amplify — To speak largely or copiously; to be diffuse in argument or description; to dilate; to expatiate; -- often with on or upon. Watts. He must often enlarge and amplify upon the subject he handles. South. (Webster's 1913.)