From The Collaborative International Dictionary of English v.0.48 [gcide]:
omnibus \om"ni*bus\, a.
Pertaining to or dealing with a variety of topics at one
time; as, omnibus legislation; an omnibus budget bill.
[PJC]
Omnibus bill, a legislative bill which provides for a
number of miscellaneous enactments or appropriations.
[Parliamentary Cant, U.S.]
Omnibus box, a large box in a theater, on a level with the
stage and having communication with it. [Eng.]
--Thackeray.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Omnibus \Om"ni*bus\, n. [L., for all, dat. pl. from omnis all.
Cf. Bus.]
1. A long vehicle, having seats for many people; a bus.
[1913 Webster]
Note: In the 1913 Webster the term omnibus was especially
applied to, a vehicle with seats running lengthwise,
used in conveying passengers short distances.
[PJC]
2. (Glass Making) A sheet-iron cover for articles in a leer
or annealing arch, to protect them from drafts.
[1913 Webster]
3. (Printing) A volume containing collected and reprinted
works of a single author or on a single theme.
[PJC]
From WordNet (r) 3.0 (2006) [wn]:
omnibus
adj 1: providing for many things at once; "an omnibus law"
n 1: an anthology of articles on a related subject or an
anthology of the works of a single author
2: a vehicle carrying many passengers; used for public
transport; "he always rode the bus to work" [syn: bus,
autobus, coach, charabanc, double-decker, jitney,
motorbus, motorcoach, omnibus, passenger vehicle]