Final answer:
The word 'fastidious' is an adjective that describes the painter in the sentence.
Step-by-step explanation:
In the sentence above, the word fastidious is an adjective. Adjectives are words that describe or modify nouns or pronouns. They provide more information about the noun or pronoun they are attached to. In this sentence, 'fastidious' describes the noun 'painter' and tells us that the painter is very careful and attentive to detail.
Learn more about Parts of speech