Instant and Sec

Instant noun - A very small space of time.

Sec is a synonym for instant in moment topic. In some cases you can use "Sec" instead a noun "Instant". informal substitute

Nearby Words: instance, instantly, instantaneous, instancy

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

Instant is a synonym for sec in brief time period topic. You can use "Instant" instead a noun "Sec", if it concerns topics such as shortest interval of time.