- noun a regular rising and falling of the sea, in a twice-daily rhythm
- Shift in the distribution of the Earth’s waters under the gravitational influence of the Moon and (to a lesser extent) the Sun, and, by analogy, similar gravitational effects in other astronomical systems
Origin & History of “tide”
Tide originally meant ‘time’ – as in the tautologous ‘time and tide wait for no man’. like the related German zeit, Dutch tijd, and Swedish and Danish tid, all of which mean ‘time’, it comes from a prehistoric Germanic *tīdiz. this was derived from the base *tī- (source also of English time), which in turn went back to the Indo-European base *dī- ‘divide, cut up’ – so etymologically the word denotes ‘time cut up, portion of time’. This notion of a ‘period’ or ‘season’ is preserved in now rather archaic expression such as Christmastide, Whitsuntide, and noontide. The application to the rise and fall of the sea, which emerged in the 14th century, is due to the influence of the related middle Low German tīde and Middle Dutch ghetīde, where it presumably arose from the notion of the ‘fixed time’ of the high and low points of the tide. Betide (13th c.) was formed from the now archaic verb tide ‘happen’, a derivative of the noun.