Azaborane usually refers a borane cluster where BH vertices are replaced by N or NR (R stands typically for H or organic substituent). Like many of the related boranes, these clusters are polyhedra and can be classified as "closo-", "nido-", "arachno-", etc..
Within the context of Wade's rules, NR is a 4-electron vertex, and N is a 3-electron vertex. Prominent examples are the charge-neutral "nido"- (i.e. ) and "closo"- (i.e. ).
Azaboranes can also refer to simpler compounds including iminoboranes (RB=NR', where R and R' stand typically for H or organic substituent) and borazines.