Which word means formal and explicit approval?

The term that means formal and explicit approval is "imprimatur." This word originates from the Latin phrase meaning "let it be printed," and it is commonly used in contexts such as publishing or ecclesiastical settings, where official permission or endorsement is necessary before something can be made public. An imprimatur serves as a mark of approval that provides credibility and assurance that the content has met specific standards or criteria.

In contrast, the other options do not convey the sense of formal approval. "Privation" refers to a state of lacking basic necessities or comforts, which is unrelated to approval. "Solicitous" describes someone who is showing concern or care for someone else, lacking the formal endorsement aspect. "Probity" refers to adherence to the highest principles of integrity and honesty, which addresses moral uprightness rather than a formal endorsement or approval.