early 14c., "froth, foam, thin layer atop liquid" (implied in scomour "scummer, shallow ladle for removing scum"), from Middle Dutch schume "foam, froth," from Proto-Germanic *skuma- (source also of Old Norse skum, Old High German scum, German Schaum "foam, froth"), which is perhaps from PIE root *(s)keu- "to cover, conceal" on the notion of "that which covers the water."
Especially (late 14c.) "impure foam or extraneous substance that rises to the surface when liquid boils." Hence any sort of impure froth, and the sense deteriorated to "film of dirt," then simply "dirt, filth." The meaning "lowest class of humanity" is from 1580s; scum of the Earth is attested by 1712. The Germanic word was adopted in Romanic (Old French escume, Modern French écume, Spanish escuma, Italian schiuma). As a verb, "remove the scum from," late 14c.
early 15c. skimmen, "lift the scum from by a sliding motion, clear (a liquid) from matter floating on the surface" (the agent noun skimmer, for the utensil used, is attested from late 14c.), from Old French escumer "remove scum," from escume (Modern French écume) "scum," from a Germanic source (compare Old High German scum "scum," German Schaum; see scum).
The meaning "throw (a stone) so as to skip across the surface of (water)" is from 1610s. The meaning "move lightly and rapidly over the surface of" is from 1650s, from the motion involved in skimming liquid; that of "glance over carelessly, pass over lightly in perusal" (in reference to printed matter) is recorded by 1799. Related: Skimmed; skimming.
Proto-Indo-European root meaning "to cover, conceal."
It forms all or part of: chiaroscuro; cunnilingus; custody; cutaneous; cuticle; -cyte; cyto-; hide (v.1) "to conceal;" hide (n.1) "skin of a large animal;" hoard; hose; huddle; hut; kishke; lederhosen; meerschaum; obscure; scum; skewbald; skim; sky.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kostha "enclosing wall," skunati "covers;" Greek kytos "a hollow, vessel," keutho "to cover, to hide," skynia "eyebrows;" Latin cutis "skin," ob-scurus "dark;" Lithuanian kiautas "husk," kūtis "stall;" Armenian ciw "roof;" Russian kishka "gut," literally "sheath;" Old English hyd "a hide, a skin," hydan "to hide, conceal; Old Norse sky "cloud;" Old English sceo "cloud;" Middle High German hode "scrotum;" Old High German scura, German Scheuer "barn;" Welsh cuddio "to hide."
"a thick substance concreting in liquors; the lees or scum concreted" [Johnson], 1530s, probably from Middle Dutch modder "filth, dregs," from PIE *meu- (see mud).
type of soft white clay, 1784; from 1789 as "tobacco pipe with a bowl made of baked meerschaum clay," from German Meerschaum, literally "sea-foam," so called from its frothy appearance; from Old High German mari "sea" (see mere (n.1)) + scum "scum" (see skim (v.)). A loan-translation of Latin spuma maris, itself said to be a loan translation of Greek halos akhne, from Persian kaf-i-darya.
"dross, scum, superfluous matter, separated from that which is useful," especially a waste product of an animal or vegetable body, 1590s, from French récrément (mid-16c.) or directly from Latin recrementum, as if from a verb *recernere, from re- (see re-) + cernere "to sift, separate" (from PIE root *krei- "to sieve," thus "discriminate, distinguish"). Related: Recremental (1570s); recrementitious.
1892, in cookery sense in reference to a frothy dish stiffened with egg whites, etc., from French mousse, from Old French mousse "froth, scum," from Late Latin mulsa "mead," from Latin mulsum "honey wine, mead," from neuter of mulsus "mixed with honey," related to mel "honey" (from PIE root *melit- "honey"). Meaning "preparation for hair" is from 1977, so called for resemblance of the substance. As a verb in this sense from 1984. Related: Moussed.
