The Saaroa and Kanakanabu, two smaller minority groups who share their territory with an Isbukun Bunun group, have also adopted Bunun as their vernacular.
Bunun is a verb-initial language and has an Austronesian alignment system or focus system. This means that Bunun clauses do not have a nominative-accusative or absolutive-ergative alignment, but that arguments of a clause are ordered according to which participant in the event described by the verb is 'in focus'. In Bunun, four distinct roles can be in focus:
* the agent: the person or thing that is doing the action or achieving/maintaining a state;
* the undergoer: the person or thing that is somehow participating in the action without being an agent; there are three kinds of undergoers:
** patients: persons or things to whom an action is done or an event happens
** instruments: things which are used to perform an action
** beneficiaries : the persons for whom an action is done or for whom an event happens
* the locative participant: the location where an action takes place; in languages with a Philippine-style voice system, spatial location is often at the same level in a clause as agents and patients, rather than being an adverbial clause, like in English .
Which argument is in focus is indicated on the verb by a combination of prefixes and suffixes .
* a verb in agent focus is often unmarked, but can get the prefix ''ma-'' or - more rarely - ''pa-'' or ''ka-''
* a verb in undergoer focus gets a suffix ''-un''
* a verb locative focus gets a suffix ''-an''
Many other languages with a focus system have different marking for patients, instruments and beneficiaries, but this is not the case in Bunun. The focussed argument in a Bunun clause will normally always occur immediately after the verb and is in the Isbukun dialect marked with a post-nominal marker ''a''.
Bunun has a very large class of auxiliary verbs. Concepts that are expressed by auxiliaries include:
* modality and volition
* relative time
* question words
* sometimes numerals
In fact, Bunun auxiliaries express all sorts of concepts that in English would be expressed by adverbial phrases, with the exception of time and place, which are normally expressed with adverbial phrases.
Bunun is an agglutinative language and has a very elaborate set of derivational affixes , most of which derive verbs from other word classes. Some of these prefixes are special in that they do not only occur in the verb they derive, but are also foreshadowed on a preceding auxiliary. These are called lexical prefixes or anticipatory prefixes and only occur in Bunun and a small number of other Formosan languages.