I went through this whole thing to show you that American cheese is a real food only to stumble on this term in the definition lol
Pasteurized process cheese is the food prepared by comminuting and mixing, with the aid of heat, one or more cheeses of the same or two or more varieties, except cream cheese, neufchatel cheese, cottage cheese, lowfat cottage cheese, cottage cheese dry curd, cook cheese, hard grating cheese, semisoft part-skim cheese, part-skim spiced cheese, and skim milk cheese for manufacturing with an emulsifying agent prescribed by paragraph
of this section into a homogeneous plastic mass. One or more of the optional ingredients designated in paragraph (d) of this section may be used.
https://www.ecfr.gov/current/title-21/part-133#p-133.169(a)(1)
It’s so easy to forget that plastic has other definitions than “made of plastic” lol.