1) a Bolshevik, or someone accused of having Bolshevik (communist) leanings).
2) (more commonly) an adjective meaning that someone is very assertive in the pursuit of something and/or hostile to authoritarian manoeuvres by others. A bolshy person gets cross if confronted and is likely to say "what's it to you?", "mind your own business" and stuff like that a lot.
3) also the name of a short-lived youth magazine run by the Alliance for Workers' Liberty.
He was getting stroppy with me, so I started getting bolshy.
A lot of students get a bit bolshy after a few pints.
Based off of the word "bourgeoisie" (boosh wa zi) which means "the middle class, typically with reference to its perceived materialistic values or conventional attitudes."
omg did you see she got that new iPhone? Yeah shes so Booshy!