What is the term MOAB means in MW3

The abbreviation of M.O.A.B means "Massive Ordnance Air Blast" but it unofficially means "Mother of All Bombs". A hidden killstreak which you can get for 25 (or 24 if you are using hardline) killstreak. This killstreak is automatically activated, so if you are using assault, support and/or specialist strike package, it counts. The M.O.A.B does not end the game. It kills all the enemy and enemy air supports, then EMP's them when they spawn. You do not eliminate your teammates or yourself when using this. You get a big amount of XP for that. Lastly, you cannot use your killstreak or pointstreak to help you increase the kills toward M.O.A.B. Instead, you must use your weapons, and only your weapons, to increase the killstreak. The specialist strike package is helpful because you are gaining only perks, and once you have the specialist bonus (8 killstreak and/or pointstreak) you have acquired all the perks, making you invincible, if you can stay alive as much as possible.