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Published: 1st September 2021

Citation: Astronist Institution. (2021). Siderialism. Available: Last accessed [enter date e.g. 1st Sept 2021].


noun  Astroeschatology

belief in the coming of the Sideria, especially its imminent occurrence.


Siderialist | sʌɪˈ dɪərɪəlˈ ɪst | adjective & noun
Siderialistic | sʌɪˈ dɪərɪəlˈ ɪstɪk | adjective
Siderialistically | sʌɪˈ dɪərɪəlˈ ɪstɪk(ə)li | adverb
Siderian | sʌɪˈ dɪərɪən | adjective & noun
Siderianism | sʌɪˈ dɪərɪənɪz(ə)m | | noun


Astro-English: from Astronese, the word siderialism is formed by the use of the adjective sidereal to mean “distant stars” but is nonetheless broadened in the context of Astronism to relate to “the astronomical world” in a more general sense; conjoining this word with the suffix -ism to denote “a belief” comes to form a term that is broad enough to be used in various instances throughout Astronist terminology.

Encyclopaedic entry for “Siderialism” on

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