legitimise
le-git-i-mise
verb
To make something lawful, acceptable, or valid, often by official approval.
"The new law will legitimise their claims."
Thesaurus
Synonyms: legalise, legitimate, decriminalise, decriminalize, legalize, legitimize, legitimatise, legitimatize
Antonyms: criminalise, criminalize, illegalise, illegalize, outlaw