'Lactobacillus' originates from Latin, specifically the words 'lac' meaning 'milk' and 'bacillus' meaning 'small rod.'

'Lactobacillus' was derived from the Latin term 'bacillus' and combined with 'lacto-' to describe its milk-related properties.

Initially, it referred to any rod-shaped bacterium associated with milk, but now it specifically refers to a genus of bacteria involved in fermentation.