tide (n.) Look up tide at Dictionary.com
Old English tid "point or portion of time, due time, period, season; feast-day, canonical hour," from Proto-Germanic *tidiz "division of time" (cognates: 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, cut up" (cognates: Sanskrit dati "cuts, divides;" Greek demos "people, land," perhaps literally "division of society," daiesthai "to divide;" Old Irish dam "troop, company").

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."
tide (v.) Look up tide at Dictionary.com
"to carry (as the tide does)," 1620s, from tide (n.). Usually with over. Earlier it meant "to happen" (Old English; see tidings). Related: Tided; tiding.