What Does the Word Untrustworthiness Mean?

: not dependable or worthy of confidence : not trustworthy an untrustworthy person an untrustworthy source.

Is there such a word as untrustworthiness?

Untrustworthiness is part of a person's character--something that cannot be addressed by expressions of contrition or policy reforms. Dictionary browser ?

What does duplicitous mean in English?

Duplicity comes from a Latin word meaning "double" or "twofold," and its original meaning in English has to do with a kind of deception in which you intentionally hide your true feelings or intentions behind false words or actions.