Segundo

Segundo is a term with several related meanings, most commonly used to denote time and order. In the International System of Units (SI), the second (segundo in Spanish, segundo in Portuguese) is the base unit of time. It is defined by the fixed number of periods of radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom: 9,192,631,770 periods. The symbol for the second is s. This definition ties the unit to a precise atomic process, ensuring consistency across measurements and locations.

Etymology and linguistic usage

The word segundo derives from Latin secundus, meaning following or next in order. In Romance languages, it operates as an adjective and noun to express sequence or rank. In Spanish, “segundo” can indicate the second item in a list (segundo, tercero), the time unit just described, or, in compounds, a deputy or assistant role (el segundo al mando). The feminine form is segunda, used with feminine nouns.

Other meanings and cross-language notes

Beyond time, segundo functions as the ordinal form of “second” in many languages, such as Italian (secondo) and Portuguese (segundo). In music, “segundo” may appear as a label for a second interval or part. The concept of a second appears across disciplines, from scheduling and measurement to ranking and subordination.

See also

Time measurement, cesium-133, SI base units, ordinal numbers, linguistic cognates.