Genitive Case
From Scottish Gaelic Grammar Wiki
The noun and its modifiers such as adjectives are marked with genetive case:
Tha mi a' sireadh an leabhair hig ghuirm. be.PRES.IND 1s PROG searching.VN ART book.GEN small.GEN blue.GEN 'I am looking for the small blue book.'
When more than two nouns are combined together, the last noun gets genetive case:
Doras na sgoile(adh) door ART school.GEN 'The door of the school'
Doras oifis ceannard na sgoile(adh) door office head ART school.GEN 'The office door of the head of the school'