picket

1. A stake driven into the ground. (countable, uncountable) · a picket fence
2. A type of punishment by which an offender had to rest his or her entire body weight on the top of a small stake. (countable, uncountable)
3. A tool in mountaineering that is driven into the snow and used as an anchor or to arrest falls. (countable, uncountable)
4. 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. (countable, uncountable)
5. A sentry. (countable, figuratively, uncountable)
6. A protester positioned outside an office, workplace etc. during a strike (usually in plural); also the protest itself. (countable, uncountable) · Pickets normally endeavor to be non-violent.
7. The card game piquet. (uncountable)

Plural pickets