Below are the words that matched your query...
Unaccountable
- not to be accounted for or explained; "perceptible only as unaccountable influences that hinder progress"; "an unexplainable fear"  
 - free from control or responsibility  
 
Unexplainable
- not to be accounted for or explained; "perceptible only as unaccountable influences that hinder progress"; "an unexplainable fear"  
 
Unexplained
- having the reason or cause not made clear; "an unexplained error"  
 - not explained; "accomplished by some unexplained process"  
 
Underlying
- in the nature of something though not readily apparent; "shortcomings inherent in our approach"; "an underlying meaning"  
 - being or involving basic facts or principles;
 - located beneath or below  
 - be or form the base for  
 - lie underneath  
 
Understood
- implied by or inferred from actions or statements; "gave silent consent"; "a tacit agreement"; "the understood provisos of a custody agreement"  
 - fully apprehended as to purport or meaning or explanation; "the understood conditions of troop withdrawal were clear"  
 - know and comprehend the nature or meaning of; "She did not understand her husband"; "I understand what she means"  
 - perceive (an idea or situation) mentally; "Now I see!"; "I just can't see your point"; "Does she realize how important this decision is?"; "I don't understand the idea"  
 - believe to be the case;
 - make sense of a language; 
 - be understanding of; "You don't need to explain--I understand!"  
 
Unexpressed
- not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"  
 
Unsaid
- not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"  
 - take back what one has said; "He swallowed his words"  
 
Unstated
- not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"  
 - Not said
 
Unuttered
- not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"  
 
Unverbalized
- not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"