olemus
(1a) raamat füüsilise üksusena, sealhulgas teoseosana
Wiktionary:
4. a bound book
5. a single book of a publication issued in multi-book format, such as an encyclopedia
The letter "G" was found in volume 4

(1b) = loogiline draiv
Wiktionary:
11. (computing) an accessible storage area with a single file system, typically resident on a single partition of a hard disk