well , there are some words specifically used in TUGs.
and here are definitions for some words, which TUG newbies will find them helpful
Gag - anything used to prevent a person from making noise. There are ball gags where a big ball is fitted and strapped in the mouth, then tape gags where a an adhesive or bondage tape is plastered around the lips. Cleave gags, a cloth is tied around the head passing between the teeth of the person. There are many other type of gags too, and gags are used in combos to make them more effective.
Bound - Tied (simple as that)
sadist - a type of person who gets pleasure from hurting another. (you can find them in chloroformmeplease's stories)
hogtie - where the persons wrists are tied to his/hers feet behind him/her.
spread eagle - when the person is tied spread out, with their arms and legs stretched, mostly on the bed where the wrists and feet are tied to the bed posts.
mummified - when the person is tied from head to toe with tape, of course there is a space for the person to breath.
well folks, thats some of the definitions I came up with. If there are more words, you are free to add them below in your comments.