大功

great merit / great service

see 大夫[dai4 fu5]

big; large; great / older (than another person) / eldest (as in 大姐[da4 jie3]) / greatly; freely; fully / (dialect) father / (dialect) uncle (father's brother)

meritorious deed or service / achievement / result / service / accomplishment / work (physics)

successfully accomplished (project or goal) / to be highly successful