Formal:
* Veracious: implies a commitment to truthfulness and accuracy.
* Authentic: suggests genuineness and originality.
* Frank: implies straightforwardness and honesty.
* Candid: similar to frank, but with a suggestion of openness and directness.
* Forthright: implies directness and boldness in speaking the truth.
* Genuine: emphasizes authenticity and lack of pretense.
Informal:
* Honest: the most common and general term.
* Sincere: implies genuine feelings and intentions.
* Straightforward: similar to frank, but with less emphasis on bluntness.
* True: emphasizes the accuracy and reality of something.
* Real: implies authenticity and lack of pretense.
Other options:
* Credible: implies believability and trustworthiness.
* Reliable: suggests dependability and consistency in being truthful.
* Trustworthy: implies that someone is worthy of trust.
* Integrity: suggests a strong moral compass and adherence to ethical principles.
The best word to use will depend on the context and the specific meaning you want to convey.