The following weighty question flashed across my mind this morning: which word is to 'aunt' as 'avuncular' is to 'uncle'? A little Internet pokey-wokey brought me to materteral.
Maternal, paternal, fraternal, sororal, avuncular, materteral!
Hard to pronounce and useless for purposes of communication with hoi polloi, but interesting nonetheless.
I pity those who interests are exhausted by the utile.