parent-n; 3 Senses

Sense Number 1: guardian or protector of a child

Commentary: PARENT[+role][+social][+guardian]
NOTE: a guardian can also be a biological ancestor, but the emphasis is on the social role.

Mary's alcoholic mother was never a parent to her.
Sally is taking her new boyfriend home to meet her parents.
The child's adopted parents willed their entire estate to him.
Being a parent can sometimes be a thankless job.

WordNet 3.0 Sense Numbers: 1

Sense Number 2: the ancestor or predecessor of something

Commentary: ROLE[+role][+ancestor]
NOTE: a biological parent can also play a social guardian role, but emphasis is on biological link.

She discovered that her real parents were from England, not France.
Although his parents both have green eyes, Bill has brown eyes.
Their parent company operates out of Atlanta.
He is tracing the parent languages of an Indonesian creole.
The parent of this Zinfandel root stock comes from Italy originally.

WordNet 0.0 Sense Numbers: 2a, 2c

Sense Number 3: the source or cause of something

Commentary: ROLE[+role][+causal]

Necessity is the parent of invention.
War is the parent of famine.
He is one of the parents of modern portfolio theory.

WordNet 0.0 Sense Numbers: 2b