"Fork up" is an informal phrase that means to hand over, pay, or provide something reluctantly or unwillingly. Its antonyms, or words that have the opposite meaning, include words such as "give willingly," "voluntarily offer," or "donate." Other antonyms for "fork up" are "withhold," "keep back," or "refuse to provide." These words express the opposite of the action of "forking up," as they signify the act of holding onto something and not giving it away. Overall, the antonyms for "fork up" demonstrate different attitudes towards giving and providing, ranging from willingness and generosity to stinginess and reluctance.