Alien
Alien adjective - Not being a vital part of or belonging to something.
Usage example: it's completely alien to her nature to wish evil of anyone
Essential
Essential adjective - Being a part of the innermost nature of a person or thing.
Usage example: an unquenchable belief in the essential goodness of most people
How words are described
Both words in one sentence
-
The baby turns out to be a human/alien hybrid and essential in the conspiracy she and Mulder have been uncovering for the last eight years.
Source: Babies Make Everything Better -
While useful for taking down aliens for interrogation, it's also essential for seizing any piece of handheld alien technology, which otherwise self-destructs upon the wielder's death.
Source: Video Game / XCOM: Enemy Unknown -
Alien Kudzu: The Primes flood local waters with their base cells, which are essential to reproduction; these invasive organisms kill off most other things that are in the water with them.
Source: Literature / Commonwealth Saga
Cite this Source
Essential and Alien. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/alien/essential
Alien & Essential. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/alien/essential>.
Essential or Alien. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/alien/essential.
Google Ngram Viewer shows how "alien" and "essential" have occurred on timeline