This is the 14547th most frequent German word.
leiblichen
"Leiblichen" means "biological" or "blood-related" when referring to family relationships.
Here, 'leiblicher' specifies a direct familial relationship based on birth.
Er ist mein leiblicher Bruder.
He is my biological brother.
The word 'leiblicher' here clarifies that the father is one's birth parent, which might distinguish him from a stepfather or adoptive father.
Mein leiblicher Vater lebt in einer anderen Stadt.
My biological father lives in another city.
In this sentence, 'leibliche' is used to emphasize that the mother mentioned is the one related by blood, as opposed to an adoptive or foster parent.