Not related to or not involving stars; the opposite of astral, now virtually obsolete.
From 'a-' (not, without) + 'astral' (relating to stars, from Latin 'astralis'). This is a rare negative formation that never became common in English, probably because people simply didn't need the opposite of 'astral.'
This word is almost certainly a historical curiosity—a logical but unnecessary formation that probably appeared once or twice in old philosophical texts and then disappeared. It's like the word-formation equivalent of a species that never quite evolved.
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