An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements.
Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item.
An expression of favorable acceptance and encouragement; a compliment that also condones.
Approval, or permission to proceed.
A go-ahead to commit a crime, specifically to carry out a hit on someone (i.e. to kill).
A traffic light in its green state (indicating that vehicles may proceed).