Ghosting - when someone (normally that you've begun a relationship with, and slept with) just disappears. Deletes and blocks from messaging apps, won't answer the phone etc, because they want to break it off but don't want to actually have the discussion.
I think people overuse the term to define anyone that just stops replying to messages, as this is common in OD when you're having discussions with several people - it's more specifically when you were in a relationship with them and they just disappear.
Breadcrumbing is when someone's level of communication drops dramatically, from chatting many times a day, to just the occasional message or interaction on Facebook or something. Basically they're keeping someone on the back burner so they can pick things up again when they choose.
Mooseburgers (MB) is also overused :) as it was originally defined as offering up sex on a plate to a man who would lose interest because he'd rather hunt for moose himself, and getting something without the need to hunt for it makes it seem less desirable. On here it's just used as a term for sex.
Lovebombing - a term used for the act of someone being incredibly full-on, planning the future together in the incredibly early stages of a relationship, romanticising and basically overwhelming your doubts and reservations through force of will. Then rapidly losing interest later on.
Future faking - I'm not completely sure I understand this, apart from what it seems to imply. Maybe it's the same as lovebombing?
Irons - to have several irons in the fire, messaging several people at once on OD, possibly multidating. It's a common technique in online dating. Chats and interactions run out of steam so often and quickly that it's possibly wise to have several people on the go at once.