There is no word in the English language that starts with Y and ends with Z.
science words that starts with a
Zebra
There are words that end with z and begin with most letters. However, there are no words in the English language that begin with y and end with z.
sex
hertz
Zealous is a positive word. It starts with the letter z.
5 letter words that start with Z: zealot
zoologico zapatos
I don't believe that there are any proper English words that fit this criteria.
Zoe
Zubat and zigzagoon.