a plain (landform) is 'une plaine' in French. The noun is feminine.
The English adjective plain (ordinary) is 'ordinaire' which can be used as both a masculine or feminine word. In the sense of 'downright', it is spelled 'direct / directe'. As an adverb meaning 'simply', it is translated 'simplement' and isn't masculine nor feminine as adverbs have no gender in French.
Is the French word case feminine or muscling
The french word "la" is a feminine word, in fact, it is the state of all the feminine words in french.
The word 'comedie' in French is feminine.
The French word "trousse" is feminine.
The French word "brosse" is feminine.
The French word "aide" is feminine.
"Sorte" is a feminine word.
The French word for Africa, "Afrique," is feminine.
"Une lettre." The word is feminine.
Rome is a feminine proper noun in French.
une dent is a feminine noun in French.
Une baguette is a feminine noun in French.