Short form of "Not to worry"

When you eat dirt for the first time and leave your family to build a shack in the woods

Used in the app Farm Story. If there are no plants left to water, a person will put "ntw" on their wall. They usually do this to get more people to come to their own farms.

An abbreviation for New Technology Weapon. A 20mm or 14.5mm sniper rifle made in South Africa.

NTW is an abbreviation that originates in Scotland that stands for "Nail The Whale".
The exact origin is unsure but it's thought to have originated in the Glasgow area (possibly South side of Glasgow) and realtes to the sexual conquest of some girl who was smitten by a guy called Skoot Mackoo.