'libelous' originates from the Latin word 'libellus,' a diminutive of 'liber,' meaning 'book' or 'document.'

'libellus' transformed into the Old French word 'libelle,' and eventually became the modern English word 'libelous' through Middle English.

Initially, it meant 'a small book or document,' but over time it evolved into its current meaning of 'defamatory.'