The term 'THE PAIR' can be solved by the word 'BOTH', which is a four-letter word. 'BOTH' is an adverb that is used to refer to two people or things together. It is often used to indicate that two people or things are equal in some way, such as when they are doing the same thing or have the same characteristics. It can also be used to emphasize that two people or things are different from each other.