'bacteroides' originates from Modern Latin (New Latin), specifically from the Greek word 'baktērion' meaning 'small rod' and the suffix '-oides' meaning 'resembling'.

'bacteroides' was formed in New Latin for use in bacteriology (early 20th century) by combining Greek 'baktērion' + '-oides' and became established as the genus name 'Bacteroides' for a group of rod-shaped anaerobic bacteria.

Initially it meant 'resembling a small rod' (i.e., 'rod-like'), but over time it evolved into the scientific genus name for a specific group of anaerobic, rod-shaped bacteria commonly found in the gut.