When you want to refer to something that follows the next thing, the term "next but one" is used. There are several other phrases in the English language that can be used instead of "next but one" depending on the context. For example, "second in line," "two down," "second after next," "the one after the next one," and "penultimate" all refer to the second item after the next one. These terms can be used in various settings from discussing events, appointments, and even people or objects in a sequence. Using some of these synonyms can help to vary your language and prevent repetition.