albumen

noun4

1. •
   Synonym of egg white (“(uncountable) the clear fluid part of an egg surrounding the yolk, being mostly the protein albumin and water, which turns stiff and white when beaten or cooked; (countable) the white of a particular egg”).

   • Beautiful fresh eggs, boiled gently to perfection, are a true gourmet experience. The albumens (whites) will be tender and slightly 'curdy', the yolks still soft and silky. — 2021
2. •
   (no longer used) A colourless, soluble protein found in blood plasma, egg white, etc.; albumin; (countable) chiefly preceded by a descriptive word: one form of such a protein.

   • The various elements found in food are the following: Starch, sugar, fats, albumen, mineral substances, indigestible substances. — 1892
3. •
   (no longer used) The endosperm of seeds of most flowering plants, especially when found in mature seeds.

   • In his [William Griffith's] summary of the novel points of structure, &c., indicated in his paper, he mentions […] 3rd. The confluence of the albumina of several sacks into one albumen. — 1845
4. •
   (no longer used) Synonym of blood plasma (“the clear fluid portion of blood in which the blood cells are suspended”).

   • [W]henever the bloud is quiet or ceases from motion, vvhether vvithin or vvithout the body of an Animal, the red and grumose part of it soon curdles, and is separated from the serose or albumen; […] — 1683