A unit of time equal to one sixtieth of a minute. The time needed for a cesium-133 atom to perform 9,192,631,770 complete oscillations. See Table at measurement. A brief interval of time; a moment. See Synonyms at moment. Mathematics A unit of angular measure equal to one sixtieth of a minute. Coming next after the first in order, place, rank, time, or quality. Repeating an initial instance: a second chance. Reminiscent of one that is well known: a second George Washington; a second Waterloo. Alternate; other: every second year. Inferior to another; subordinate: second vice president at the bank; a leader second to none. Music Having a lower pitch. Music Singing or playing a part having a lower range. Having the second-highest ratio. Used of gears in a sequence. The ordinal number matching the number 2 in a series. One of two equal parts. One that is next in order, place, time, or quality after the first. An article of merchandise of inferior quality. Often used in the plural. The official attendant of a contestant in a duel or boxing match. See Synonyms at assistant. Music The interval between consecutive tones on the diatonic scale. Music A tone separated by this interval from another tone. Music A combination of two such tones in notation or in harmony. Music The second part, instrument, or voice in a harmonized composition. An utterance of endorsement, as to a parliamentary motion. The transmission gear or gear ratio used to produce forward speeds higher than those of first and lower than those of third in a motor vehicle. Informal A second serving of food. Baseball Second base.