Crucial is a synonym of Significant. Significant is the opposite of Slight. Slight is a synonym of Little. 
Free is related to Republic. Republic is related to Official. Official is related to Event. Event is related to Race. 
Crucial <--Synonym--> Significant <--Antonym--> Slight <--Synonym--> Little 
Free <--RelatedTo--> Republic <--RelatedTo--> Official <--RelatedTo--> Event <--RelatedTo--> Race 