What is the part of speech for word back?

The word "back" can be several parts of speech depending on its context. Here are some possibilities:

1. Adverb: This is the most common use, indicating direction or position.

* "Please step back."

* "I'm going back home."

2. Adjective: Describing something that is at the rear or in the past.

* "The back door was locked."

* "I have a backache."

3. Noun: Refers to the rear part of something.

* "She sat in the back of the car."

* "He turned his back on me."

4. Verb: Can indicate a return to a previous position or state.

* "The train backed up."

* "He backed away from the fight."

5. Preposition: This is less common, but can be used to mean "in return" or "in response to."

* "I gave him back his money."

* "He wrote back to me."

To determine the correct part of speech for "back," you need to consider the context of the sentence.