What is the meaning of the word "adopt"?

Definitions:

to choose and follow verb
- We adopted the new rules yesterday; you can't expect us to have memorized them by today!
to put into dramatic form verb
- I adopted a book for a screenplay and sold it to a major studio.
to take into one's family verb
- They adopted two children.
to take on a certain form, attribute, or aspect verb
- I adopted aspects of the styles I researched.
to take on titles, offices, duties, or responsibilities verb
- I adopted the role of a manager and got a pay raise.
to take up and practice as one's own verb
- I adopted their mannerisms.
to take up the cause, ideology, practice, method, of someone and use it as one's own verb
- I quickly adopted a similar way of making sandwiches.