IPA: /ˈlæstˌbɔrn/
KK: /ˈlæstˌbɔrn/
Referring to the youngest child in a family or group.
She is the lastborn in her family and often gets spoiled by her older siblings.
The youngest child in a family or the last child born to parents.
As the lastborn, she often received special attention from her older siblings.
Lastborn → It is formed from "last" (from Old English *last*, meaning final or most recent) and "born" (from Old English *beran*, meaning to bear or give birth). The word "lastborn" refers to the youngest child in a family, the one who is born last.
Think of the 'final' child ('last') being 'born' ('born') — that's why lastborn means the youngest child.
No commonly confused words.