The term BE UNTRUTHFUL WITH can be broken down into three crossword solutions: LIE (3 letters), LYING (5 letters), and LIETO (5 letters). LIE is a verb meaning to make an untrue statement with the intention of deceiving someone. LYING is a noun that refers to the act of telling a LIE. LIETO is an adverb that describes the manner in which a LIE is told, such as deceitfully or untruthfully. All three words refer to the act of being untruthful with someone.