Definition of grandmaternal in English:

grandmaternal

adjective

humorous
  • Of, relating to, befitting, or resembling a grandmother; grandmotherly.

Origin

Mid 18th century; earliest use found in Richard Brookes (fl. 1721–1763), physician and author. From grand- + maternal.

Pronunciation

grandmaternal

/ɡran(d)məˈtəːnl/