green light

the approval by someone in authority for the doing of something <we were given the green light to use the town commons for our fund-raiser> Synonyms allowance, authorization, clearance, concurrence, consent, granting, permission, leave, license (or licence), sanction, sufferance, warrantRelated Words imprimatur, seal, signature, stamp; accreditation, certification; liberty, pass; concession, patent, permit; tolerance, toleration; acceptance, acquiescence, agreement, assent, OK (or okay); accord, grantNear Antonyms denial, refusal, rejection, revocation; taboo (also tabu); injunction, veto; deterrence, discouragement, repression, suppression; ban, embargo, exclusionAntonyms interdiction, prohibition, proscription