This is the definition I tend to go by:
Jailbreaking
A
jailbreak is the act or tool used to perform the act of breaking out of a
chroot or
jail in
UNIX-like operating systems or bypassing
digital rights management (DRM). In the former case it allows the user to see files outside of the filesystem that the administrator intends to make available to the application or user in question. In the context of DRM, this allows the user to run arbitrarily defined code on DRM-encumbered devices as well as break out of chroot-like restrictions. DRM-encumbered devices such as the
iPhone have repeatedly been subject to jailbreaks, allowing the execution of arbitrary code, but have had those jailbreaks disabled by vendor updates.
[1][2] It was only in the wake of the popularity of the
iPhone and
iPod Touch that the term
jailbreaking became well known in popular culture worldwide.