Soap Opera Rapid Aging Syndrome (also SORAS or "rapid aging") is the term used to describe the aging of a television character (usually an infant or child, but also sometimes a teenager) that is faster than they should be aging, given the timeline of the show. The process is usually done to allow for more rapid character development, and to allow the writers to develop new storylines for the character.
Although the process originated in and is most common in soap operas, it has also been used in prime time comedy and drama series. In soap operas, it is nearly always done by recasting the role after the character has been absent for a time, with a new actor appearing at the character's newly "SORAS'ed" age. In the case of prime time series, the SORAS procedure usually occurs in between seasons, with a new, older actor appearing when the show returns.
The term was coined by Soap Opera Weekly founding editor in chief Mimi Torchin in the early 1990s. It's generally used to refer to cases where a character's rapid aging happens off-screen without any explanation, rather than to storylines in science fiction and fantasy series where a character is shown as being rapidly aged due to technology, magic or non-human biology.
The phenomenon has led to a newer term, de-SORAS, which refers to the opposite effect – when characters remain the same age for an unusually long period of time, or even get younger.