to bring up (a child of other parents) as one's own child after undergoing certain legal formalities

to take up and begin to use (e.g. a strategy)

Try to adopt a less dogmatic tone

to take over (e.g. a belief) from somebody else and use it as one's own

adopt the customs of another country

to vote to accept (something)

adopt a constitutional amendment

said of a constituency: to nominate (somebody) as a Parliamentary candidate

Brit said of a local authority: to assume responsibility for the maintenance of (e.g. a road)