(a.) Involving surds; not capable of being expressed in rational   numbers; radical; irrational; as, a surd expression or quantity; a surd   number. 
                        
                    
                    
                        
                        
                            (a.) Net having the sense of hearing; deaf. 
                        
                    
                    
                        
                        
                            (a.) Unheard. 
                        
                    
                    
                        
                        
                            (a.) Uttered, as an element of speech, without tone, or proper   vocal sound; voiceless; unintonated; nonvocal; atonic; whispered;   aspirated; sharp; hard, as f, p, s, etc.; -- opposed to sonant. See   Guide to Pronunciation, //169, 179, 180. 
                        
                    
                    
                        
                        
                            (n.) A quantity which can not be expressed by rational numbers;   thus, Ã2 is a surd. 
                        
                    
                    
                        
                        
                            (n.) A surd element of speech. See Surd, a., 4.