re·fine 
/rɪˈfaɪn/ verb
re·fines; re·fined; re·fin·ing /rɪˈfaɪn/ verb [+ obj] 1 : to remove the unwanted substances in (something)
▪ refine oil/sugar 2 : to improve (something) by making small changes
▪ The inventor of the machine spent years refining the design. ▪ The class is meant to help you refine your writing style.
▪ refine oil/sugar
▪ The inventor of the machine spent years refining the design. ▪ The class is meant to help you refine your writing style.
— re·fin·er noun, plural re·fin·ers [count]
▪ oil/sugar refiners [=companies that refine oil/sugar]
▪ oil/sugar refiners [=companies that refine oil/sugar]
— refining noun [noncount]
▪ oil production and refining
▪ oil production and refining
