The second (symbol: s) is a unit of time derived from the division of the day, first into hours, then into minutes, and lastly into seconds, for a total of 24 × 60 × 60 = 86 400 seconds per day. That definition, based on 1⁄86400 of a rotation of the Earth, is still used by the Universal Time 1 (UT1) system. The current and formal definition in the International System of Units (SI) is more ...

Understanding the Context

Ordinal numbers in English show the position or order of things—like first, second, third, and so on. They’re used all the time in everyday English, whether you’re talking about dates, competitions, floors in a building, or steps in a process. In this complete guide, you’ll learn how to form ordinal numbers, how to use them correctly in sentences, and how they’re different from ... The meaning of SECOND is next to the first in place or time.

Key Insights

How to use second in a sentence. A light flashing once per second. The second (symbol: s), is a unit of time. There are 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a day. This tradition dates back to the Babylonians.

Final Thoughts

In science, a second is the time it takes for a caesium atom to vibrate 9,192,631,770 (around 9 billion) times. Scientists measure the second this way because the length of a day changes all ... SECOND definition: 1. immediately after the first and before any others: 2. the position in which a person finishes a…. Learn more.

second (third-person singular simple present seconds, present participle seconding, simple past and past participle seconded) (transitive, UK) To transfer temporarily to alternative employment.