A boot is a type of footwear and a specific type of shoe. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clearly distinguishable from the rest of the sole, even if the two are made of one piece. Traditionally made of leather or rubber, modern boots are made from a variety of materials. Boots are worn both for their functionality – protecting the foot and leg from water, extreme cold, mud or hazards (e.g., work boots may protect wearers from chemicals or use a steel toe) or providing additional ankle support for strenuous activities with added traction requirements (e.g., hiking), or may have hobnails on their undersides to protect against wear and to get better grip; and for reasons of style and fashion. In some cases, the wearing of boots may be required by laws or regulations, such as the regulations in some jurisdictions requiring workers on construction sites to wear steel-toed safety boots. Some uniforms include boots as the regulated footwear. Boots are recommended as well for motorcycle riders. High-top athletic shoes are generally not considered boots, even though they do cover the ankle, primarily due to the absence of a distinct heel. In Britain, the term may be used to refer to football (soccer) cleats.
IV. iv.651 (360,7) [boot] that is, _something over and above_, or, as we now say, _something to boot_.
BUT if Disk A is in the system, OSX will boot from Disk B as the ** boot** disk, but then it'll still make Disk A the ** root** disk, meaning if you do a df - k/, or diskutil info/, you will notice Disk A is mounted as "/"!
The entry in the menu letting you boot to one or the other is in c: \boot. ini.
Incidentally, the term "boot camp" itself has undergone a semantic recalibration, and now primarily denotes the period between the X Factor auditions and the live shows, as opposed to a training academy for military recruits.
In essence, the machine has to kick start itself, “pull itself up by its own bootstraps” before it can start working; hence the term boot.