zeal
There is not a SINGLE word in the English words starting with 'z' that are related to the topic energy Lynn605's answer: actually yes there is zen its religious meditation using spiritual energy
Zephyr- a mild, dry and gentle breeze.
zoology
ZLECK
Zillionaire, zombie and zone are words. They begin with Z and end with E.
zap - kill
enzyme
quiz
zealous
zookeeper
coz
zaniestzealotzeitgeistzestzestiestzibetzigguratzionistzippiestzitzitheristzithernistzoograftzoologistzoophilistzootomistzymologist