Why is the male version of tiers used for a female word: une bouteille

Hi Blanche,

As this question has already been asked in the Q&A, please take a look at the following link which should also answer your query -

https://progress.lawlessfrench.com/questions/view/in-the-example-j-ai-bu-un-tiers-de-la-bouteille-the-audio-speaker-is-a-woman-and-the-word-bottle-is

Hope this helps!