adjective. 
                    Lacking worldly experience and understanding, especially.
                  
                
                  
                    adjective. 
                    Simple and guileless; artless.
                  
                
                  
                    adjective. 
                    Unsuspecting or credulous.
                  
                
                  
                    adjective. 
                    Showing or characterized by a lack of sophistication and critical judgment.
                  
                
                  
                    adjective. 
                    Not having experienced or been subjected to something, as.
                  
                
                  
                    adjective. 
                    Not previously subjected to experiments.
                  
                
                  
                    adjective. 
                    Not having previously taken or received a particular drug.
                  
                
                  
                    noun. 
                    One who is artless, credulous, or uncritical.