That depends, in "to own a house" it is used as a verb, in "his own house" it is an adjective.
Prefixes don't have their own part of speech.
Verbs have their own part of speech.
in - preposition the - article house - noun
The House is a proper noun. It describes a specific house.
"Haunted house" is a noun phrase.
Own is a verb.
Verb
Noun because its an object
The word "house" meaning "a building" is a noun. The word "house" meaning "to put in a house" is a verb.
Salleysue's is a possessive noun (Salleysue's house).
Still is an adverb in that sentence.
Owned is a past tense verb.