Sack is the opposite of Employ. Employ is related to Offer. Offer is related to Sacrifice. 
Forgive is derived from Give. Give is the opposite of Get. Recover is a type of Get. Rally is a type of Recover. 
Sack <--Antonym--> Employ <--RelatedTo--> Offer <--RelatedTo--> Sacrifice 
Forgive --DerivedFrom--> Give <--Antonym--> Get <--IsA-- Recover <--IsA-- Rally 