verb
The part of speech shown on the dictionary entry for the word "vestibule" is a noun.
Shown is the past participle of the verb show.
Adjective
noun
A verb.
A dictionary will tell you the part of speech for each word. For example, the entry for "dictionary" will state noun.
The word "superficial" is shown on the dictionary entry as an adjective.
"Has shown" is a verb phrase. "Has" is the helping verb (in present perfect tense), and "shown" is the past participle form of the verb "show."
The word "superficial" is an adjective.
Vial comes up as a noun.
The word "superficial" is typically listed as an adjective in a dictionary entry.
The word experimen can be a noun or a verb.