Premier and première are reserved for the absolute first. Inside compound ordinals (21st, 31st, 41st, 51st, 61st, 81st, 101st) French switches to unième. The rule is strict and gender-invariable on unième.
Updated June 2026
French
English
Form
Note
Audio
le premier livre
the first book
premier
Absolute first. Masculine. Abbreviated 1er.
la première page
the first page
première
Absolute first. Feminine. Abbreviated 1re.
le vingt et unième siècle
the 21st century
unième
Compound ordinal. Premier never appears inside a compound.
la trente et unième édition
the 31st edition
unième
Same; unième even for feminine, the form is gender invariable.
le quarante et unième arrondissement
the 41st arrondissement
unième
Hypothetical Paris example; rule is the same as 21st and 31st.
When do you use premier and when do you use unième?
Premier (masculine) and première (feminine) are reserved for the absolute first: the first book, the first time, the first floor. Unième appears only inside compound ordinals: 21st, 31st, 41st, 51st, 61st, 81st, 101st. Premier never enters a compound. The Académie française codifies this strictly: vingt et unième, never vingt et premier.
Is unième masculine or feminine?
Invariable. Unième works for both genders. Vingt et unième livre (masculine), vingt et unième page (feminine). Only premier inflects (premier / première). This is one of the few French ordinals where gender does not show.
How do you say 21st century in French?
Le vingt et unième siècle. With hyphens after the 1990 rectifications: le vingt-et-unième siècle. Both spellings are accepted. The abbreviated form is XXIe siècle (Roman numeral + e).
Why is it not vingt et premier?
Historical convention. French treats ordinals built on the unit one as taking -unième rather than dropping in premier. The same applies in other Romance languages: Italian ventunesimo, Spanish vigesimo primero. The Académie française dictionary lists only vingt et unième.