1660s, "part of a pedestal between the base and the cornice," from Italian dado "die, cube," from Latin datum (see die (n.)). Meaning "wood paneling on the lower part of a wall in a room" is by 1787.
Entries linking to dado
die n.
"small cube marked on each face with spots numbering from one to six, used in gaming," early 14c. (as a plural, late 14c. as a singular), from Old French de "die, dice," which is of uncertain origin. Common Romanic (cognates: Spanish, Portuguese, Italian dado, Provençal dat, Catalan dau), perhaps from Latin datum "given," past participle of dare "to give" (from PIE root *do- "to give"), which, in addition to "give," had a secondary sense of "to play" (as a chess piece); or else the notion is "what is given" (by chance or Fortune).
The numbers on the opposite sides always add up to seven; otherwise there is no uniformity to their arrangement. Sense of "engraved stamping block or tool used for stamping a softer material" is from 1690s. Perhaps so called because they often were used in pairs (to impress on both sides, as of a coin).
Figurative phrase the die is cast "the decisive stem is taken" is from 1630s, in reference to the throw of the dice. The expression translates Latin alea iacta est (or iacta alea est), famously uttered by Caesar when he crossed the Rubicon.
*do-
*dō-, Proto-Indo-European root meaning "to give."
It forms all or part of: add; anecdote; antidote; betray; condone; dacha; dado; data; date (n.1) "time;" dative; deodand; die (n.); donation; donative; donor; Dorian; Dorothy; dose; dowager; dower; dowry; edition; endow; Eudora; fedora; Isidore; mandate; Pandora; pardon; perdition; Polydorus; render; rent (n.1) "payment for use of property;" sacerdotal; samizdat; surrender; Theodore; Theodosia; tradition; traitor; treason; vend.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dadati "gives," danam "offering, present;" Old Persian dadatuv "let him give;" Greek didomi, didonai, "to give, offer," dōron "gift;" Latin dare "to give, grant, offer," donum "gift;" Armenian tam "to give;" Old Church Slavonic dati "give," dani "tribute;" Lithuanian duoti "to give," duonis "gift;" Old Irish dan "gift, endowment, talent," Welsh dawn "gift."