means A picket is a pointed wooden stake, a soldier or small unit posted on watch, or a person stationed outside a workplace during a protest or strike.

from From French 'piquet,' a pointed stake, from 'piquer,' to prick or pierce — the same family as 'pike' and 'picket fence.' Soldiers driving such stakes to tether horses or guard a perimeter gave the word its military sense of a sentry on watch; from there it marched into labor disputes, where strikers 'stand picket' outside the gates much as guards once stood their posts.