If you work one substance into another or work it in, you add it to the other substance and mix the two together thoroughly. Gradually pour the liquid into the flour, working it in carefully with a wooden spoon Work in the potato and milk until the mixture comes together Work the oil gradually into the yolks with a wooden spoon
add by mixing or blending on or attaching; "work in the butter and the dough will get the right consistency"; "In his speech, the presidential candidate worked in a lot of learned words