In the example "J'ai bu un tiers de la bouteille". The audio speaker is a woman and the word bottle is feminine-why use the masculine version tiers?

Question

Thank you.

Cécile Janty-Davies · Accepted Answer

Hi Robin,
In the case of one third , meaning 33.33% (1/3) of something, the noun un tiers de stands on its own and doesn't agree with the noun it applies to (or the person speaking).
e.g. 
Un tiers des électeurs ne s'est pas déplacé pour voter = One third of the electorate didn't go and vote
Un tiers de la famille a été décimé par les inondations = One third of the family was decimated by the floods
Un tiers de la foule était composé de femmes = A third of the crowd was made up of women
Hope this helps!

Robin Eschenbruecher · Answer

I appreciate the reply in regard to tiers, but tierce is used once in an example and I am not sure when I should use it.

Cécile Janty-Davies · Answer

Hi Robin,
The adjective 'tiers/tierce' will only be used in certain expressions like 'tierce personne' or 'tierce partie' to mean a third party -
Also in the following expressions -
Le tiers-monde = The third World
Le Tiers-état = The third estate/tier of society 
The noun 'tierce' is used in some card games to denote three cards following each other.
It has very limited use...
Hope this helps!

Robin Eschenbruecher · Answer

Merci!

Ally Harris · Answer

If you're saying that most of the time tiers does not agree in gender, I think that should be added to the main lesson. The way it is currently worded - "You use tiers (masculine) or tierce (feminine)" - with no additional follow-up information, suggests that it does agree in gender. If I hadn't read this comment I would have basically just learnt it completely wrong.

Jessica Smith · Answer

I'm confused about "tiers" being a 'un mot invariable'.

In this "J'ai bu un tiers de la bouteille" tiers is surely a noun, and thus an adjective would have to agree with it? After all we don't make bouteille agree with vin in "J'ai bu une bouteille du vin" and it has exactly the same structure.

Cécile Janty-Davies · Answer

Hi Jessica,
I have rephrased my answer regarding -
un tiers de quelque chose = a third  (1/3) of something
by it doesn't agree with the object it refers to.
Thank you for pointing out, hope this clarifies things.

Jessica Smith · Answer

Thank you, although, I'd probably be a bit more precise about which bit is the noun.

«Un tiers de» is a phrase of [indefinite article] [noun] [preposition]. (You could have «le tiers de», as well as phrases with other prepositions, like «un tiers à ...» and «un tiers pour ...».)

(I can't immediately think of any [article] [noun] [noun] combinations in French. English has things like "a boat race" or "a steel bar" whilst french seems to use [article] [noun] [preposition] [noun], as in «une course de bateux» or «une coque en acier».)

edit: The lesson on compound nouns with à,de and en is probably worth pointing people to: Compound nouns formed with prepositions à/de/en in French

Lori Godon Trewolla · Answer

AI gave me an answer I can understand easily -

In French, "une tierce" is the feminine form of "tiers" (meaning "third"). It is almost exclusively used in set expressions across specific fields: [1, 2]

In law and administration: Used in the phrase "une tierce personne" (a third party/witness) or "une tierce partie".In music: Refers to a "third", which is an interval between three notes (e.g., une tierce majeure or une tierce mineure).In fencing: Refers to the third of eight defensive hand positions (called la tierce).In card games: Refers to a sequence of three cards of the same suit (e.g., une tierce majeure).In religion: Refers to the daytime prayer (Canonical hour) traditionally recited at 9 a.m