-most /məʊst $ moʊst/ BrE AmE suffix [in adjectives]
nearest to something:
the northernmost town in Sweden (=the town that is furthest to the north)
the topmost branches of the tree
-most /məʊst $ moʊst/ BrE AmE suffix [in adjectives]
nearest to something:
the northernmost town in Sweden (=the town that is furthest to the north)
the topmost branches of the tree
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012