'Zephyr'- (noun) 

a gentle breeze
Example: If not for the zephyrs that were blowing and cooling us, our room would’ve been unbearably hot.

'Zeal' - (noun)

 enthusiasm, passion, or eagerness

 Example: She showed great zeal in preparing for the moot court competition.

'Zealous' - (adjective)

 full of energy or devotion; passionate

 Example: The zealous student never missed a single class.

'Zenith' - (noun)

 the highest point or peak

 Example: The company reached the zenith of success under her leadership.

'Zany' - (adjective)

 funny, silly, or eccentric

 Example: The comedian’s zany antics made everyone laugh uncontrollably.

'Zap' - (verb)

 to destroy, kill, or pass quickly

 Example: The superhero zapped the villain with a single beam of energy.

'Zest' - (noun)

 great enthusiasm or enjoyment

 Example: She approached the project with zest and creativity.

'Zigzag' - (noun/verb)

 a pattern with sharp turns; to move in sharp turns

 Example: The child ran in a zigzag across the playground.

'Zombie' - (noun)

 a fictional undead creature; someone who acts without thinking

 Example: The villagers were afraid of the zombie in the story.

'Zone' - (noun/verb)
 an area or region; to focus attention
 Example: The city is divided into different zones for administrative purposes.

'Zodiac' - (noun)
 a circle of twelve divisions used in astrology
 Example: According to the zodiac, she is a Libra.

'Zoology' - (noun)
 the scientific study of animals
 Example: He pursued zoology because of his love for wildlife.

'Zestful'- (adjective)
 full of energy and enthusiasm
 Example: The zestful volunteers completed the project ahead of schedule.

'Zigzagged' - (verb)

 moved with sharp turns from side to side

 Example: The cyclist zigzagged through the traffic to reach the finish line.

'Zoom' - (verb)
 to move quickly or suddenly
 Example: The car zoomed past us on the highway.

'Zeptosecond' - (noun)

 an extremely short unit of time (10^-21 seconds)

 Example: Scientists measured the reaction in a zeptosecond for precision.

'Zero-sum' - (adjective)

 a situation where one’s gain is another’s loss

 Example: Negotiations over the territory were zero-sum, with no compromise possible.

'Zymurgy' - (noun)
 the branch of chemistry dealing with fermentation
 Example: He studied zymurgy to improve beer brewing techniques.

'Zeitgeist' - (noun)
the defining spirit or mood of a particular period in history
Example: The film perfectly captures the zeitgeist of the 1990s.

'Zenithward' - (adverb)
toward the highest point; upward
Example: The rocket soared zenithward, disappearing into the clouds.