The possessive form for the noun trail is trail's.
Example: We seem to have arrived at the trail's end.
Trail
The singular possessive form is word's, for example the word's definition.
possessive form of the word glass: glass'
possessive form of the word Congress: Congress'
possessive form for the word holders: holders'
possessive form of the word Cathi: Cathi's
The possessive form of the word fairy is fairy's.
The possessive form of the word dictionary is dictionary's.
the possessive form of the word Cathie: Cathie's
The possessive form is Lindbergh's.
The possessive form is weaver's.
The possessive form for the interrogative pronoun who is whose.
The possessive form for the word 'word' is word's.