Mater (Guild Master): Latin word for Mother.
Elder: This person has been with us ever since our Perfect World days. They will always have this rank (or a rank similar) in any game we play.
Veteran: Above in rank from Soldier. We trust you a lot and you are basically on par with Elder rank. You must fill out a resume-esque application to earn this rank
Soldier: Same as Guildie, but with inviting privileges and more guild bank withdrawals. An Elder or Veteran may promote you to this rank if they feel like you've earned it.
Domesticum (Guildie): Latin word for a member of a family or household. You are trusted enough to have more guild privileges. You are now allowed to withdraw more money and items from the guild bank.
Novus (Newbie): Latin word for new, fresh, inexperienced. You're new to the guild! Once we trust that you aren't here to just steel stuff out of the guild bank you'll be promoted to Guildie. This is basically a trial rank so we can get to know you. :D
Alt: Someone's Alt (a character they use besides their main).
Officer Alt: A Guild Leader, Elder, or Veteran's Alt
Malus: Latin word for bad, evil, wicked. You were caught breaking some sort of rule. Shame on you! You'll be watched carefully and it'll be decided whether or not you should be kicked from the guild. If you start to behave you'll start over as a Newbie..
Subject to change with different games.