I put more work into this than I thought I would have to. =(
White Mage - One of the job classes you can choose. White Mage heals people's wounded Hit Points. When your Hit Points hit 0, you're dead.
Valkurm Dunes - Popular area for people to level up from level 10-20. Usually has many new players.
Warrior - Another job class you can choose. Warrior can keep the monsters you fight from hitting the weaker job classes, or do lots of damage to the monster.
Skillchain - Vital to being a good player. A Skillchain involves players using Weapon Skills in succession to deal massive damage to an enemy.
Weapon Skill - Skills used during battle to damage an enemy. Differ depending on the weapon you use.
Subjob - A secondary job you can use in addition to your main job class. Must be quested to use.
Ghoul - Monster that holds one of the items needed to complete the Subjob quest.
WAR - Acronym for Warrior.
MNK - Acronym for Monk.
WHM - Acronym for White Mage.
RDM - Acronym for Red Mage.
BLM - Acronym for Black Mage.
Jeuno - Central town, a sort of hub for selling and buying items, as well as forming parties. Can be very difficult to reach unless you are a higher level player.
Wiped out - All party members killed.
Gil - The currency in Final Fantasy XI.
LS - Acronym for LinkShell. A group of friends who can speak with each other privately inside their own chat.
Teleports - Teleport spells that can take you to 6 various central locations of the world.
Zilart - The first expansion to Final Fantasy XI. It added many new areas.
THF - Acronym for Thief, another job class you can choose to be.
Flee - An ability exclusive to Thieves, it allows your character to run faster to escape enemies or travel more quickly.
Telepoint - Where characters who used Teleport spells would arrive at.
AF - Acronym for Artifact. Artifact equipment is higher level and very hard to obtain.
Tell - Private chat between two characters.
^^ - A happy face. Each ^ represents an eye.
/cry - An action you can make your character do. The character will move as though it were crying.
Vana'Diel - The world of Final Fantasy XI.
pearl - Short for Linkpearl. Used to communicate in a Linkshell.
lol - An acronym for laughing out loud.
Davoi, Beaucedine, Sarutabaruta - Areas in the world of Vana'Diel.
Cap Quest - Quest to lift the level cap from your character. These are only in effect post level 50.
NPC - Non-Player Character. Characters in the game who were placed there by the creators, and do not have real people controlling them.
Beastmen - The main villains in Final Fantasy XI, they strive to destroy the world.
Ninja - An advanced job class, can only be obtained after reaching level 30. This class is popular for its ability to dodge enemy's attacks, and are very well liked because of it.
Tank - Term for a character who keeps the enemy focused on him or her self so that it does not attack weaker job classes.
Conned - Term for "Checked". Monsters can con Too Weak(Many levels lower than you), Easy Prey(Only a few levels lower), Decent Challenge(1 or 2 levels lower), Even Match(Your level), Tough(1 or 2 levels higher), Very Tough(A few levels higher), or Incredibly Tough(Many levels higher). The +'s indicate High Evasion and High Defense. The more +'s, the more powerful the monster is.
ISP - Not related to Final Fantasy XI. It is an acronym for Internet Service Provider. Examples would be America Online, Yahoo, etc.