*da-
*dā-, Proto-Indo-European root meaning "to divide."

It forms all or part of: betide; daimon; Damocles; demagogue; demiurge; democracy; demography; demon; demotic; endemic; epidemic; eudaemonic; geodesic; geodesy; pandemic; pandemonium; tidal; tide (n.) "rise and fall of the sea;" tidings; tidy; time; zeitgeist.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dati "cuts, divides;" Greek demos "people, land," perhaps literally "division of society," daiesthai "to divide;" Old Irish dam "troop, company;" Old English tid "point or portion of time," German Zeit "time."