Sec and Split second

Sec noun - 1/60 of a minute; the basic unit of time adopted under the Systeme International d'Unites.

Split second and sec are semantically related. in moment topic. In some cases you can use "Split second" instead a noun "Sec", when it comes to topics like brief time period, shortest interval of time.

Split second noun - A very small space of time.

Sec and split second are semantically related. You can use "Sec" instead a noun phrase "Split second".