* Noun: A flat piece of material, often wood, used for a variety of purposes.
* Example: "He sat on the board of the ship."
* Verb: To get on or into a vehicle or aircraft.
* Example: "The passengers boarded the plane."
* Noun: A group of people who manage or direct an organization.
* Example: "The board of directors met to discuss the budget."
* Verb: To cover something with a layer of something else.
* Example: "They boarded up the windows."
Therefore, the part of speech of "board" can only be determined by its context in a sentence.