Neutral:
* Untruthful: This is a straightforward and neutral way to describe someone who tells lies.
* Inaccurate: This emphasizes the falsehood of the statement rather than the person's character.
* Fabricator: This term implies a more deliberate and creative construction of a falsehood.
* Deceptive: This focuses on the act of misleading, rather than the person themselves.
* Misleading: This emphasizes the unintended consequences of the lie.
Negative:
* Prevaricator: This suggests a tendency to evade the truth, often through wordplay or ambiguity.
* Dissembler: This implies a more calculated and manipulative form of deception.
* Con artist: This implies a deliberate attempt to defraud someone.
* Fraud: This is a strong term that implies a serious violation of trust.
Informal:
* Stretch the truth: This is a more casual way to describe someone who exaggerates or embellishes the truth.
* Fibber: This is a more lighthearted term, often used for small, harmless lies.
* Bullshitter: This is a more informal and negative term, suggesting someone who speaks with confidence without any regard for the truth.
Ultimately, the best euphemism to use depends on the specific context and the desired level of formality and negativity.
Important Note: It's important to be mindful of the power dynamics in a situation. Using euphemisms for "liar" can sometimes be perceived as patronizing or even condoning the behavior.