tide

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To betide; befall.
• noun The periodic variation in the surface level of the oceans and of bays, gulfs, inlets, and estuaries, caused by gravitational attraction of the moon and sun.
• noun A specific occurrence of such a variation.
• noun Flood tide.
• noun Tidal force.
• noun Something that increases, decreases, or fluctuates like the waters of the tide.
• noun A large amount or number moving or occurring in a mass.
• noun A surge of emotion: synonym: flow.
• noun A time or season. Often used in combination.
• noun A favorable occasion; an opportunity.
• intransitive verb To rise and fall like the tide.
• intransitive verb Nautical To drift or ride with the tide.
• intransitive verb To carry along with the tide.

from The Century Dictionary.

• To happen; betide.
• To drift with the tide; specifically (nautical), to work in or out of a harbor, etc., by taking advantage of the tide and anchoring when it becomes adverse.
• To drive with the tide or current.
• To carry through; manage.
• To succeed in surmounting: with over: as, to tide over a difficulty.
• noun In forestry, a freshet. In the Appalachian region logs are rolled into a stream and a ‘tide’ is awaited to carry them to the boom.
• An obsolete preterit of tie.
• An erroneous Middle English form of tidy.
• noun Time; season.
• noun Fit time or season; opportunity.
• noun Eccles., a season of the church year; in a narrower sense, a feast-day; a festival: as, Whitsuntide (the whole octave or the day only); Hallowtide.
• noun Mass; office; service.
• noun A definite period of time; specifically, a day or an hour; in mining, the period of twelve hours.
• noun The periodical rise and fall of the waters of the ocean and its arms, due to the attraction of the moon and sun.
• noun and the same where the moon is in the nadir is
• noun But where the particle as seen from the center of the earth is 90° from the moon, the attraction is a little less than the attraction at the center, being m/(r+ a) in place of m/r, and is also not parallel to the latter; so that it is accelerated downward toward the earth by an amount equal to Compounding these accelerations with the accelerations of the weights of the particles, we see that the resultant for any particle points less toward the moon than the line from the particle to the earth's center. But the surface of the water must be perpendicular to the resultant attraction; hence that surface must bulge out in a prolate form on the line through the centers of the moon and earth. The extreme difference in depth of the water would be about 20 inches, or, substituting the sun for the moon, it would be about 9 inches. If after the prolate form had been produced the disturbing body were to be suddenly annihilated, the ocean, supposing it covered the whole earth, would be thrown into a state of oscillation between a prolate and an oblate form. The time of the oscillations would depend on the depth of the water, and they would gradually die out from viscosity and other resistances. If the moon were to move round the water-covered earth on the equator, similar free oscillations would be set up and would gradually die out, but at the same time other motions would be forced and would not die out. Supposing first, for the sake of simplicity, that the effects of viscosity were very great, the water would be permanently raised all round the equator so as to increase the ellipticity of the surface of the sea, and such an effect, on a minute scale, is in fact produced. But, besides that, the equatorial section of the form of the water would be elliptical, the water continuing to pile up as long as it was at all drawn toward the moon; so that high tide would not be reached until 4 hours 45 minutes after the moon had crossed the meridian. If the resistance is not so great the time of high tide will be earlier or later, according as the natural oscillations are quicker or slower than the forced motion. The resistance will also produce small component oscillations of periods one half and one third of those of the principal oscillations. Every inequality in the motion of the sun and moon produces its own distinct component tide; but the magnitudes of the tides are very different from the magnitudes of the inequalities. The forms of the continents and of the sea-bottom affect the range of the tides in two ways. In the first, place, they form basins in which the waters are susceptible of free stationary oscillations of various periods. Now, it is a known theorem of dynamics that forced vibrations attain large amplitudes when their periods are nearly the same as those of free vibrations, but are very small when their periods are nearly double those of free vibrations. In the second place, the continents in many cases force the ocean into canals, in which the tides take the form of progressive waves of translation, which will be greatly increased by a narrowing and still more by a shoaling of the channel in the direction of their progression. In this case there are distinct cotidal lines. In the North Atlantic the semidiurnal tide is large, but much larger in the eastern and northern parts than on the southern and western sides. The diurnal tides, on the other hand, are remarkably small. High tide occurs in the northern parts three or four hours earlier than in the southern; and between them, about Nantucket, there is little tide, and in many places four tides a day. In the Gulf of Mexico the semidiurnal tides are very small, and the diurnal tides are alone sensible. In a few places, as Tahiti, in the Pacific, and Courtown, in county Wexford, Ireland, the lunar tides almost disappear, so that high tide never occurs many hours from noon or midnight, and near such places there are others where the tides almost altogether vanish.
• noun Ebb and flow; rise and fall; flux and reflux.
• noun Flow; current; stream; flood; torrent.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb obsolete To betide; to happen.
• intransitive verb To pour a tide or flood.
• intransitive verb (Naut.) To work into or out of a river or harbor by drifting with the tide and anchoring when it becomes adverse.
• transitive verb To cause to float with the tide; to drive or carry with the tide or stream.
• noun obsolescent Time; period; season.
• noun The alternate rising and falling of the waters of the ocean, and of bays, rivers, etc., connected therewith. The tide ebbs and flows twice in each lunar day, or the space of a little more than twenty-four hours. It is occasioned by the attraction of the sun and moon (the influence of the latter being three times that of the former), acting unequally on the waters in different parts of the earth, thus disturbing their equilibrium. A high tide upon one side of the earth is accompanied by a high tide upon the opposite side. Hence, when the sun and moon are in conjunction or opposition, as at new moon and full moon, their action is such as to produce a greater than the usual tide, called the spring tide, as represented in the cut. When the moon is in the first or third quarter, the sun's attraction in part counteracts the effect of the moon's attraction, thus producing under the moon a smaller tide than usual, called the neap tide.
• noun A stream; current; flood.
• noun Tendency or direction of causes, influences, or events; course; current.
• noun obsolete Violent confluence.
• noun (Mining) The period of twelve hours.
• noun tidal movements of the atmosphere similar to those of the ocean, and produced in the same manner by the attractive forces of the sun and moon.
• noun See under Inferior, a.
• noun the interval between the occurrences of two consecutive maxima of the resultant wave at the same place. Its length varies as the components of sun and moon waves approach to, or recede from, one another. A retardation from this cause is called the lagging of the tide, while the acceleration of the recurrence of high water is termed the priming of the tide. See Lag of the tide, under 2d Lag.
• noun a dial to exhibit the state of the tides at any time.
• noun (Naut.) A place where the tide runs with great velocity, as through a gate.