Some missed terms.
Rebound: This is when a human player blocks a beast and when the human player goes to hit the blocked beast that is stuned the beast takes a swing as soon as stun wears off and lands it. Your basically getting a free hit as beast and should always do this. Theres no reason not to get your rebound.

Turtling.
When a human commander builds his base to the point where its almost invunerable to summoner/siege attacks placing the shiled usually as far back from the enemy's fire as possible. Like a turtle retreating into his shell.
Pmine(powermine)
The act of a team mining stone very quickly with there backs against a sub/garrison placed directly next to a stone mine. In laymen terms, your getting stone super fast.
Whore.
Any person who abuses game mechanics/weapons/items/buffs to get kills soley this way. BuffWhore/SummWhore/SiegeWhore/CoilWhore/ListaWhore you get the idea.
Farming(I think someone said this)
The act of an individual or team harvesting kills in great numbers suffering few deaths at the expense of the other team. Usually due to the fact that one team is greatly outteched our outmanuvered and at a huge tactical disadvantage.
Bow with scope. My favorite

lol. This refers to the Marksman Bow. Guess this ones kinda obvious. Maybe just a fun term

Xbow with spokes: Lol this is really old. only a few people used this one. This refers to the ballista. Just another fun term.
Terms not seen much but more of a tactic/skill:
3 shot.
When a predator 3 hit kills a legonaire quickly. 1,2,3 hit combination really fast to the point the legonaire has no time to heal or even knows WTF is going on. (It takes 3 hits from a pred at level 3 experience to kill a lego).
1 shot.
One of the crappiest ways to die. Ballista or summoner or behemoth or electrical buff death. Basically you have no chance to survive full health or not. You get hit by one of these bad boys and its lights out. Its when these weapons are abused against someone in repetition that savage game play suffers IMO.
Escape: When a human player escapes a rebound from a beast player by any tactic. The most well used tactic is to hold shift (run) while moving backwards as you swing to hit the stunned beast in hopes that midswing when the beast becomes unstunned he wont be able to reach you. Also can do a spin around his back as your hitting him stunned in hopes he cannot turn and hit you midswing when he becomes unstunned.
Freeswing IMO:
Its simple. You get a free swing(Freehit). You really dont have a clue if its going to land therefore its luck. Theres no skill, your mearly assuming that a beast will leap or run in front of the swing. You have no idea if its going to work. If it lands you just got yourself a freeswing. Simple. Veterans hate this because if your fighting 1 against many noobs that really should have no way of killing you in a 1vs1 fair fight or even 1vs2or3or4 and there all freeswinging like crazy its very possible that the mear fact that there are so many blades swinging around that the noob frenzy freeswinging fest alone will kill you. lol. The power of the noob frenzy freeswinging extravaganza is amazing. Also, this can be used with skill by a skilled player and actually aimed and timed skillfully and not looked upon as bad. I.E moving backwards luring the beast in for a leap and anticipating the leap. Its only looked upon badly when you know that the guy had no idea he was going to hit you or anything at all for that matter. You mearly were leaping in the wrong place at the wrong time. Hence you gave him a freeswing(freehit more like it).