The prefix would be epi-, as in epidermis. (The outer layer of skin)
        
             
        
        
        
Perhaps 'vocabulary'? 
It is important to use vocabulary/terminology in a persuasive speech that the audience will understand.
        
             
        
        
        
Answer:
lifelessly, casually, halfheartedly, sluggishly, idly, lazily, spiritlessly, Desultorily, indolently, wearily, sleepily, listlessly, lackadaisically, tiredly, languidly.
Explanation:
these are some antonyms for laboriously which means :in a way that takes considerable time and effort.