her

We don’t traditionally think of the word her as having synonyms, but there are several situations in which it can replace—or be replaced with—another word, phrase, or series of words.

hers

Many sentences that use the word hers can be reworded to mean the same (or just about the same) thing using the possessive sense of the word her, and vice versa. Instead of saying, “Is this her book?” you could say, “Is this book hers?” Instead of saying, “Her house is on the left,” you could say, “Hers is the house on the left.”

she

Sometimes a sentence can be reworded to replace the object her with the equivalent subject she. For example, the question, “When do you expect her to arrive?” could be reworded as “When do you expect she will arrive?”

Her is commonly used after linking verbs (like is and was) in sentences like It was her that I saw on the train or It is her in that picture, but sometimes the word she is used in such constructions, such as when saying, “This is she” when answering the phone.

herself

In some cases, the word herself  is used as another way of saying her. For example, it’s common to say things like She should think for herself. Herself is also sometimes used in place of her after the words as, than, and but, as in She saw at the door a girl no older than herself and She has no one to blame but herself. 

them

Like they, them has a long history of being used to refer to an unspecified individual or to a person whose gender and other personal details are unknown or irrelevant, as in If a student is absent, they must bring in a note with them when they return to school. Sentences like this sometimes use constructions like he or she and him or her, but the use of they and them has become very common in such instances, with many people preferring them as less awkward and more inclusive.