Relating to bacteria or characteristic of bacteria; bacteriological in nature.
From bacterium + -ian suffix (from Latin), which forms adjectives meaning 'of or relating to.' Less common than 'bacterial' but appears in historical medical texts.
Language evolves, and 'bacterian' is mostly archaic now—'bacterial' became the standard term because it's shorter and clearer, showing how English naturally selects simpler forms over time.
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