The Siddur we use for Yom Tov is known as a Machzor. What does it mean and where did this originate?
The word mahzor means "cycle" (the root Ħ-Z-R means "to return"). It is applied to the festival prayer book because the festivals recur annually.
The Shulchan Aruch in OC 100 rules that prior to a holiday one must go over and prepare the text of the prayers so that he is familiar with them.
I suggest this is why holiday prayer books are called Machzor from the root Ch.Z.R. which can mean to review or to go over.
According to the Hebrew Wikipedia article "מחזור תפילה", citing Daniel Goldschmidt's preface to Shadal's Introduction to the Machzor of the Community of Rome, this term was used in medieval times to refer to prayer books that contained a comprehensive list of prayers for the entire cycle of the year (e.g. the 11th century Machzor Vitry composed by Rabbi Simcha ben Shmuel of Vitry).
Eventually, standard prayer books (often including only the standard weekday and Sabbath prayers) became called "siddurim" due to the arrangement of the prayers contained therein, and the term "machzor" either became reserved as a reference to compilations of prayers for special holidays such as the High Holy Days (especially in Germany) or retained its original meaning as a comprehensive compilation of yearly prayers (such as in Italy and Livorno).