The plural of 'astron' in some older taxonomic or mineralogical contexts, or a prefix element meaning star.
From Greek 'astron' meaning 'star.' This appears primarily as a combining element in scientific nomenclature rather than as a standalone modern English word.
This is a 'ghost word'—it barely exists in modern English except as a prefix building block in hundreds of other words, showing how ancient Greek roots live on invisibly in science!
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