In my book:
Loot is the items that come from a mob
Lot is the process of obtaining the mob (Lotting, Lot, free lot ect)
DD is a person who does dmg
DPS is how much damage that person does per second
Character: you in game character
Toon: Google loony toons

Then again people interchange the words in the genre. If you came to XIV from XI it will be characters, Lot, and DD.... if you came from WoW/Other mainstream mmo it will be toon, Loot, and dps.

I personally still find it is funny people say "looking for 3 damage per second and good to go" instead of "looking for 3 Damage Dealers and good to go". >.> Or when I tried wow at the start how I got very pissed when someone called my character a toon.