What is the distance between the notes on the staff?

eighth step

half step

whole step

quarter step

your word would be isle.

isle is an island or peninsula especially a small one.

if you add the letter "a" you get aisle, which is a passage between 2 rows of something like chairs, shelves, or something else.

violins play the melody in this section of sergei prokofiev's peter and the wolf.

hope this !