Is ostinato an Italian word

Answer 1

Yes, "ostinato" is an Italian word.

Specifically, as a masculine singular adjective, the word means "dogged, obstinate, stubborn." As a masculine singular noun, it means "obstinate, stubborn person." Its singular definite article is "l"* ("the"), and its singular indefinite article is "un, uno" ("a, one").

But either way, the pronunciation remains the same: "OH-stee-NAH-toh."

*The masculine singular definite article actually is "il." But the vowel "i" drops when the article is followed by a noun that begins with a vowel. The temporary nature of that drop is indicated by an apostrophe placed after, not before, the still-standing "l" of "il."