Time is of the essence when it comes to these two adjectives, so we'll get right to it: quick describes a speedy tempo; expeditious emphasizes promptness and efficiency, especially in the completion of a task. An expeditious answer to an inquiry is one that takes no time at all. Expeditious is easy to confuse with expedient, but the latter (expedient) is better used to describe things that are suitable or advantageous for a specific purpose, such as politically expedient statement.

To belie is to create an impression that is inconsistent with the facts or that contradicts evidence. For instance, if a friend is feeling very nervous and insecure about a presentation but somehow manages to give off an aura of nonchalant confidence while delivering it, you could say their casual, relaxed manner belies their insecurity. The core idea of belie is one of misrepresentation, though the term does not usually suggest an intent to deceive; rather it used to point out notable or striking variances or contradictions.

If a person is open about their feelings on a topic, they speak freely and hold nothing back. When someone is described as candid, it usually means they are frank, outspoken, and sincere—sometimes unpleasantly so. A candid remark is one free from reservation or disguise. Candid is also used to refer to things that are unposed and informal, such as a candid photo.