Metaphor originated from the Greek word, metaphor which simply means to transfer. Analogy on the other hand came from the Greek word, analogia which means proportion. Given these etymologies, metaphor is a figure of speech that actually transfers the meaning of one thing directly on another unit.
Medicines that are taken âas neededâ are known as âPRNâ medicines. âPRNâ is a Latin term that stands for âpro re nata,â which means âas the thing is needed.â. Itâs important to know the difference between daily and âas neededâ medicines.hese instructions should include the following information: 1  How much medicine you can take in a set period of time. 2  When to take your PRN medication. 3  When to take scheduled and PRN medications for a single health problem.
Nurses, X-ray technicians, respiratory therapists and many other healthcare workers work PRN. The initials stand for pro re nata, a Latin phrase that roughly translates to as needed or as the situation arises. A PRN employee works when called, to fill in for an absent employee or to cover a special situation.