In medicine, sterilization or neutering was a process which rendered someone unable to reproduce.
In the 2250s, a tribble neuterator, supposedly used to neuter the extremely fertile tribble species, was included in boxes of Tribbles cereal. (ST: "The Trouble with Edward")
In 2268, Hodin explained that as the Gideon birth rate continued to rise and the population grew, their planet Gideon became encased in a living mass incapable of finding rest, peace, or joy. Captain James T. Kirk asked why they hadn't introduced new techniques to sterilize men and women, but Hodin responded that it would be impossible because their organs renewed themselves. (TOS: "The Mark of Gideon")