2nd definition of 2nd in the Free Online Encyclopedia.

second, abbr. sec or s, fundamental unit of time time, sequential arrangement of all events, or the interval between two events in such a sequence. The concept of time may be discussed on several different levels: physical, psychological, philosophical and scientific, and biological.
..... Click the link for more information. in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the day day, period of time for the earth to rotate once on its axis. The ordinary day, or solar day, is measured relative to the sun, being the time between successive passages of the sun over a stationary observer's celestial meridian .
..... Click the link for more information. varies, however, the second must be defined in more precise terms. For many years it was defined as 1/86,400 of the mean solar day (see solar time solar time, time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial .
..... Click the link for more information. ), thus eliminating seasonal variations. Because the rotation of the earth itself is not constant, the second was redefined (1956) in terms of ephemeris time (ET), which is calculated from the motions of celestial bodies in accordance with the laws of motion; 1 sec is 1/31,556,925.9747 of the length of the tropical year for 1900. In 1967 the second was redefined to be 9,192,631,770 periods of vibration of the radiation emitted at a specific wavelength by an atom of cesium-133.

second¹

1. coming directly after the first in numbering or counting order, position, time, etc.; being the ordinal number of two: often written 2nd

2. denoting the lowest but one forward ratio of a gearbox in a motor vehicle

3. Music

a. relating to or denoting a musical part, voice, or instrument lower in pitch than another part, voice, or instrument (the first)

b. of or relating to a part, instrument, or instrumentalist regarded as subordinate to another (the first)

4. Brit education an honours degree of the second class, usually further divided into an upper and lower designation

5. the lowest but one forward ratio of a gearbox in a motor vehicle

6. (in boxing, duelling, etc.) an attendant who looks after a competitor

7. a speech seconding a motion or the person making it

8. Music

a. the interval between one note and another lying next above or below it in the diatonic scale

b. one of two notes constituting such an interval in relation to the other

9. goods of inferior quality

second²

a. 1/60 of a minute of time

b. the basic SI unit of time: the duration of 9 192 631 770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of caesium-133.

2. 1/60 of a minute of angle.

second [′sek·ənd]

(mathematics)

A unit of plane angle, equal to 1/60 minute, or 1/3,600 degree, or π/648,000 radian.

(physics)

The fundamental unit of time equal to 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of an atom of cesium-133. Abbreviated s: sec.

second (redirected from 2nd)

second
(redirected from 2nd)