Words related to tidal
Old English tīd "point or portion of time, due time, period, season; feast-day, canonical hour," from Proto-Germanic *tīdi- "division of time" (source also of Old Saxon tid, Dutch tijd, Old High German zit, German Zeit "time"), from PIE *di-ti- "division, division of time," suffixed form of root *da- "to divide."
Meaning "rise and fall of the sea" (mid-14c.) probably is via notion of "fixed time," specifically "time of high water;" either a native evolution or from Middle Low German getide (compare Middle Dutch tijd, Dutch tij, German Gezeiten "flood tide, tide of the sea"). Old English seems to have had no specific word for this, using flod and ebba to refer to the rise and fall. Old English heahtid "high tide" meant "festival, high day."
*dā-, Proto-Indo-European root meaning "to divide."
It forms all or part of: betide; daimon; Damocles; deal (v.); deal (n.1) "part, portion;" demagogue; demiurge; democracy; demography; demon; demotic; dole; endemic; epidemic; eudaemonic; geodesic; geodesy; ordeal; 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 dēmos "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."