Second

**Semantic type:** Temporal Concept

**Definition:** A unit of time, one of the seven base units of the International System of Units (Systeme International d'Unites, SI). The second is the duration of 919 263 177 0 periods of the specified light radiation corresponding to the transition between the two hyperfine levels of the caesium 133 atom in its ground state at 0 K. According to the convention, 60 seconds constitute one minute; 3,600 seconds constitute one hour.

**Synonyms:** - SECOND - Seconds - s - s - s - s - s - s - s - s - s - sec - sec - second - second - second - second - seconds