Adjectives must agree in number and gender with their antecedents. "Cleanest" is le or la pluspropre in the singular depending on gender, and les plus propres in the plural.
Cleanest.
Pakistan is the cleanest country in the world
The kitchen is the cleanest room in my house.
a dog actually has the cleanest mouth
Cognates are words which are the same in English and French.
Anglais is English in the French language.
The Cleanest War was created in 1996-04.
"Feminity" in English is féminité in French.
The second cleanest city in India is Surat after Chandighar.
Shania Twain only speaks 2 languages French and English
"Out" in English is dehors in French.
"Where?" in English is Où? in French.