Wormword

noun
A word, which when spoken inveigles its way into the mind of the speaker and manifests itself in his flesh.
Origin
Named for the parasitic manifestation caused by the word.
Source
Entry Taken from a Medical Encyclopedia

Xenomorph

noun
An endoparasitoid extraterrestrial species.
Origin
Derived from ksenos (foreign) and morphē (shape).
Source
Aliens

Xenonaut

noun
  1. (plural proper) An international organisation defending Earth from extraterrestrial invasion.
  2. A member of the Xenonauts defence force.
Origin
Derived from ksenos (foreign) and nautēs (traveller).
Source
Xenonauts

Xenotech

noun
A specialist in the analysis of alien technology.
Origin
Abbreviation of ‘xeno-technologist’.
Source
Gateway

Xenovox

noun
A portable device for sending and receiving voice communications over long distances.
Origin
Derived from ksenos (foreign) and vox (voice).
Source
The Witcher 3: Wild Hunt

Yuny

noun informal
The uniform clothing worn by all citizens of OneState.
Source
We

Ziphead

noun informal
A person who has been made into a cognitive computer.
Source
A Deepness in the Sky

Zippicamiknicks

noun
A one-piece female undergarment fitted with a zipper.
Origin
Portmanteau of ‘zipper’, ‘camisole’, and ‘knickers’.
Source
Brave New World