n. A pointed stake often driven into the ground to support a fence, secure a tent, tether animals, mark points in surveying, or, when pointed at the top, serve as a defense.n. A detachment of one or more troops, ships, or aircraft held in readiness or advanced to warn of an enemy's approach: "The outlying sonar picket.... was to detect, localize, and engage any submarine trying to close the convoy” ( Tom Clancy). n. A person or group of persons stationed outside a place of employment, usually during a strike, to express grievance or protest and discourage entry by nonstriking employees or customers.n. A person or group of persons present outside a building to protest.v. To enclose, secure, tether, mark out, or fortify with pickets.v. To post as a picket.v. To guard with a picket.v. To post a picket or pickets during a strike or demonstration.verb-intransitive. To act or serve as a picket.