approve, O.K., okay, sanction - give sanction to; "I approve of his educational policies"

warrant, guarantee - stand behind and guarantee the quality, accuracy, or condition of; "The dealer warrants all the cars he sells"; "I warrant this information"

side, root, pull - take sides with; align oneself with; show strong sympathy for; "We all rooted for the home team"; "I'm pulling for the underdog"; "Are you siding with the defender of the title?"

champion, defend - protect or fight for as a champion

second, endorse, indorse, back - give support or one's approval to; "I'll second that motion"; "I can't back this plan"; "endorse a new project"

back, endorse, indorse, plump for, plunk for, support - be behind; approve of; "He plumped for the Labor Party"; "I backed Kennedy in 1960"

back up, support - give moral or psychological support, aid, or courage to; "She supported him during the illness"; "Her children always backed her up"

warrant, guarantee - stand behind and guarantee the quality, accuracy, or condition of; "The dealer warrants all the cars he sells"; "I warrant this information"

sign - be engaged by a written agreement; "He signed to play the casino on Dec. 18"; "The soprano signed to sing the new opera"

co-sign, cosign - sign and endorse (another person's signature), as for a loan

visa - provide (a passport) with a visa