The word speculation derives from speculum, the magnifying glass

Evidence

The glass house metaphor captures this tension powerfully, in multiple ways. It functions as a greenhouse (offering comforting warmth) and as a magnifying glass (also coinciding thus with the meaning of speculum—the root word of speculation), combining the effects of transparency and reflection. — Aris Komporozos-Athanasiou, Speculative Communities, 442

Categorization

• DEFINE: Directly ties the etymology of speculation to the visual/reflective root, which the reader needs to nail down the ‘homo speculans’ concept.
• XREF: Connects to the reader’s stated project of tracing how speculation migrated across domains—this etymological root anchors that migration.