"The man's hat."

Translation: Hata an fhir.

[gojennifer]

Why is it fhir for man here when fir means men and fear means man.??

[scilling]

A complete rundown can be found here.

[galaxyrocker]

Because this is the genitive. It changes based on the meaning.

[Mr.Knight]

Why does fhir and fir seem interchangeable in this lesson???

[SeanGLEJohnENG]

Can this be literally "Hat of the man"?

[19O492554]

It is "the hat of the man". The genitive definite article makes both of the nouns definite.

[AnneNoone1]

Scilling
Where can i access (here)

[BLUEBELL66648]

I am thinking as a newbie.....
1.Fir (also plural of fear) is in this case the singular genitive form of fear.
2.Fir is used to form possessive (of someone, of something).
3.Use of f-H-ir because of the definite article which lenites?
Good luck all fellow learners.

[Knocksedan]

Don't get used to the idea that there is a link between the nominative plural and the genitive singular. That is only the case for some nouns.

In the nominative case, the singular is fear and an fear, and the plural is fir and na fir.

In the genitive case, the singular is fir and an fhir, and the plural is fear and na bhfear.

In the case of buachaill, you have an buachaill, with plurals buachaillí and na buachaillí, but the genitives are buachalla, an bhuachalla in the singular, with buachaillí and na mbuachaillí in the plural.

The feminine noun feoil has an fheoil, with plurals feolta and na feolta in the nominative, and feola and na feola in the genitive singular and feolta and na bhfeolta in the genitive plural. (Note the use of na in the genitive singular for a feminine noun).

(See more examples at https://forum.duolingo.com/comment/52095695)

The genitive case in English is not just used for possession (marked by 's), which indicates possession, or "of":
"she could make out the image of a man" - bhí sí in ann samhail fir a fheiceáil
(This could be "a man's image", but that can have a slightly different meaning in English).