1570s, "to heap or crowd together," probably from Low German hudern "to cover, to shelter" (of hens on chicks or nurses with children), from Middle Low German huden "to cover up," which is probably a frequentative form from Proto-Germanic *hud-, from PIE *keudh-, extended form of root *(s)keu- "to cover, conceal." Compare also Middle English hoderen "heap together, huddle" (c. 1300). Related: Huddled; huddling. The noun is from 1580s. U.S. football sense is from 1928.

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."

mid-15c., piggen, of sows, "to farrow, to bring forth piglets," from pig (n.1). By 1670s as "to huddle together in a dirty or disorderly manner, as pigs do, hence, generally, "to act or live like a pig" in any sense. Related: Pigged; pigging. Colloquial pig out "eat voraciously" is attested by 1979.

"able to be heard," 1520s, from French audible and directly from Medieval Latin audibilis "that may be heard," from Latin audire "to hear" (from PIE root *au- "to perceive"). Related: Audibly; audibility; audibleness.

As a noun, "thing capable of being heard," from 1610s. The U.S. football sense of "signal called at the line of scrimmage to change the play called in the huddle" is by 1958.