Straight edge, a flat ruler.
Tacky, sticky.
T. E. G., top-edge gilt.
Trimmed. The edges of a book are said to be trimmed when the edges of the larger (or projecting) leaves only have been cut.
Tub, the stand which supports the lying press. Originally an actual tub to catch the shavings.
Uncut, a book is said to be uncut when the edges of the paper have not been cut with the plough or guillotine.
Unopened, the book is said to be unopened if the bolts of the sheets have not been cut.
Waterproof sheets, sheets of celluloid, such as are used by photographers.
Whole binding, when the leather covers the back and sides of a volume.
Wire staples are used by certain machines in the place of thread for securing the sections.