There is a lot of overlap in meaning, and a lot of nuance and variations. But I hope this helps: Candid = honestly revealing information in a situation in which many people would not disclose information. Example: “She candidly admitted her past mistakes.” Frank = usually (but not always) has to with honestly revealing CRITICAL/NEGATIVE information to someone. Example: “His boss gave him very frank feedback about the areas in which he needed to improve.” Honest = A more general word that candid or frank, but can usually be used where “candid” or “frank” is used. Usually contrasted with dishonest. Usually used to describe a character trait of being a person who tells the truth. Direct = plainly stating what one wants or thinks, rather than being subtle or nuanced. Straightforward = very similar to direct. Blunt = like direct, but has a negative connotation of being insensitive to the feelings of the person you are speaking to. Example: “His criticism of her was so blunt it made her cry.” Outspoken == Apt to say what is on one’s mind, to speak up, not to be silent. But, a person can be dishonest while being outspoken. Outspoken does not imply honesty, but implies being very persistent or quick in expressing oneself to others. Vocal = very similar to outspoken. But, outspoken is more of a personality trait, something a person does all the time. Vocal is often used in a specific situation. Example: She is not normally an outspoken person, but she was very vocal at the most recent meeting.”