'Un anniversaire' is most frequently used as a singular, since you usually celebrate one at a time. The plural is 'des anniversaires'.
The plural of anniversary is anniversaries.
The plural form of the noun anniversary is anniversaries.The plural form of the church's anniversary is the church's anniversaries.The plural form of the noun church is churches.The plural possessive form is churches'.The plural form of church's anniversary is the churches' anniversaries.
The plural of anniversary is anniversaries.
Happy Anniversary in French is "Joyeux anniversaire"
"les vacances" (always plural)
les vacances (always plural)
'en vacances' (always plural)
"devoirs""les devoirs" (always plural)
Enterrement, funérailles (this second one is always plural)
data is spelled 'des données' (fem., nearly always plural) in French.
the ninth anniversary is translated 'le neuvième anniversaire' in French.
That is the correct spelling of "anniversary" (a recurring date).