муаллиф: author
Муаллифи ин китоб кист?
Who is the author of this book?
Муаллим дар бораи муаллифи китоб маълумот медиҳад.
The teacher gives information about the author of the book.
Bonus:
You can tell that this word is Arabic in origin because of the pattern of letters – муа??и?, where the ?? is a double consonant. Other examples would be муаллим, муаззин, муассис.
Other related words are таълиф: writing (noun), and алиф which is the first letter of the Tajik Arabic alphabet.