Relating to, characteristic of, or belonging to grandparents or the role of being a grandparent.
From grandparent plus -al, an adjective-forming suffix. This creates an adjective parallel to parental, forming in the late 20th century as society needed language for discussing grandparent-focused topics.
The rise of 'grandparental' as a common word reflects real social change—50 years ago you'd rarely hear this, but now psychologists talk about 'grandparental involvement' as a major factor in child development!
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