Chronometer depicting 59 seconds
A second, abbreviated sec, was a measurement of time equaling a fraction of a minute. On Earth a second was 1/60 of a minute. A second could be further broke down into milliseconds, microseconds, nanoseconds, and femtoseconds.
When Nadet screamed during her treatment in the imaging chamber in the sickbay aboard Enterprise and Jamin requested that the door has to be opened, Doctor Phlox told him that it last only a few more seconds. (ENT: "Terra Nova")
When preparing Captain Jonathan Archer and Commander Trip Tucker for their visit of the Vulcan monastery at P'Jem in June 2151, Sub-commander T'Pol recited the proper protocols and told them to bow slightly and observe a respectful silence for approximately five seconds after they were offered the Stone of J'Kah. (ENT: "The Andorian Incident")
Matthew Ryan told Travis Mayweather, he heard that for a split second you can actually feel yourself in both places at once during the use of a transporter. (ENT: "Fortunate Son")
Taking a neural toxin would kill the Denobulan Phlox in only a few seconds. (ENT: "Regeneration")