1. The act or action of breaking in
2. A performance or a series of performances serving as a trial run
3. An initial period of operation during which working parts begin to function efficiently

1. A casual visit or brief stop
2. One who drops in; a casual visitor. drop in

1. An encroachment or intrusion
2. An invasion or hostile attack.

ETYM Latin invasio: cf. French invasion. Related to Invade.
1. Any entry into an area not previously occupied; SYN. encroachment, intrusion.
2. The act of invading; the act of an army that invades for conquest or plunder.

ETYM Latin irruptio: cf. French irruption. Related to Irrupted.
A sudden violent entrance; a bursting in.
Breaking or bursting in.

ETYM Icel. reith a riding, raid; akin to Eng. road. Related to Road a way.
1. An attempt by speculators to defraud investors; SYN. mulcting.
2. The act of mulcting public money.
3. An attempt by professional operators to depress stock prices by concerted selling.