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