not vs not even

not

• Negates the meaning of the modified verb. 

• To no degree. 

• Used to indicate the opposite or near opposite, often in a form of understatement. 

• ‘Do they know?’ ‘I believe not’ (formal) 

• Used to indicate that the previous phrase was meant sarcastically or ironically. 

• And not. 

not even

• Introduces or constitutes a more emphatic negation or exclusion than "not". 

• Used to express strong disappointment or disapproval.