Omnibus is a Latin word meaning "for all (people)" and has two main meanings in standard English:

1. A vehicle for transporting large numbers of people. See bus.

2. A book or video collecting two or more previous works by the same author or director. See omnibus (media) .

Note: Omnibus had no plural in Latin, because it was already a plural word. In English, its plural is "omnibuses", not "omnibi", which is a solecism.