Origins
The word 'liberty' entered English around 1375 from Old French 'liberté,' from Latin 'lībertātem' (accusative of 'lībertās'), meaning 'freedom' or 'the condition of a free person.' The adjective 'līber' means 'free' or 'unrestricted,' and it may derive from Proto-Indo-European *h₁lewdʰ- (people, free people), the same root that produced Greek 'ἐλεύθερος' (eleútheros, free) and German 'Leute' (people).
In Rome, 'lībertās' was a precise legal and political concept. A 'līber' (free man) had civic rights — he could vote, hold property, and participate in public life. A 'servus' (slave) had none. Between these categories stood the 'lībertus' (freedman), a former slave who had been manumitted and gained limited civic rights. The transition from slavery to freedom was marked by the placing of a 'pileus' (a felt cap) on the freed slave's head — the 'cap of liberty' that would later become a powerful symbol in the American and French revolutions.
The Romans personified liberty as the goddess 'Lībertās,' who had a temple on the Aventine Hill. She appeared on coins holding the pileus and a rod (the vindicta used in the manumission ceremony). This image inspired the Statue of Liberty, officially 'Liberty Enlightening the World' (French: La Liberté éclairant le monde), dedicated in 1886. The sculptor Frédéric Auguste Bartholdi drew directly on the Roman iconographic tradition.
Old English Period
In English, 'liberty' and 'freedom' coexist as near-synonyms, but with different registers and connotations. 'Liberty' entered from French/Latin and tends to appear in formal, legal, and institutional contexts: 'civil liberties,' 'liberty of conscience,' 'at liberty.' 'Freedom,' from Old English, is more personal and emotional: 'freedom of movement,' 'freedom from fear,' 'free at last.' The two words complement each other rather than competing: the American vocabulary of rights uses both ('life, liberty, and the pursuit of happiness' alongside 'the four freedoms').
The Latin root 'līber' has been productive in English: 'liberal' (originally 'befitting a free person,' hence 'generous,' 'broad-minded'), 'liberate' (to set free), 'libertarian' (one who advocates maximum individual liberty), 'libertine' (one who takes excessive liberties, especially in morals), and, through Old French, 'deliver' (from Latin 'dēlīberāre,' to set free) and 'livery' (originally the provisions or allowances 'delivered' to household servants).
The phrase 'taking liberties' preserves an older sense: a 'liberty' was a privilege or exemption granted to a person or a district. In medieval England, a 'liberty' was also a jurisdictional area exempt from the authority of the sheriff — the 'Liberty of the Savoy' and the 'Liberty of the Rolls' in London preserve this meaning in their names.