reconstituted skim milk
Technical term used in food processing and dairy contexts; refers to skim milk powder reconstituted with water.
Reconstituted skim milk is made by reconstituting skim milk powder with water.
脱脂粉乳 is skim milk powder, the dehydrated form; 還元脱脂乳 is the liquid product after reconstitution.
還元乳 is a broader term for reconstituted milk (may include whole milk); 還元脱脂乳 specifically refers to the skim milk version.
Compound of 還元 (reduction/reconstitution), 脱脂 (defatting/skimming), and 乳 (milk). The term is a modern technical coinage.