Meaning

• A stake driven into the ground.

  "a picket fence"

• A type of punishment by which an offender had to rest his or her entire body weight on the top of a small stake.

• A tool in mountaineering that is driven into the snow and used as an anchor or to arrest falls.

• One of the soldiers or troops placed on a line forward of a position to warn against an enemy advance; or any unit (for example, an aircraft or ship) performing a similar function.

• (sometimes figurative) A sentry.

• A protester positioned outside an office, workplace etc. during a strike (usually in plural); also the protest itself.

  "Pickets normally endeavor to be non-violent."

• The card game piquet.

Meaning

• To protest, organized by a labour union, typically in front of the location of employment.

• To enclose or fortify with pickets or pointed stakes.

• To tether to, or as if to, a picket.

  "to picket a horse"

• To guard, as a camp or road, by an outlying picket.

• To torture by forcing to stand with one foot on a pointed stake.