G2 refers literally to Division Level or higher military intelligence.

S2 Refers to a 'Company' level intelligence.

G2 denotes a broader or higher level of information .

Used in slang the best definition is: 'Higher Intelligence or Higher Level information about a topic than is commonly known.

It particularly denotes information that is not readily available either through common information channels nor intuitive reasoning.

Specific literal Example: Our S2 reports that we need to move to this area so that we can provide flank support for Alpha company.

(The G2 is that this position is critical because Alpha company must get the enemy out of their position NOW before enemy reinforcement elements arrive.)

Example of usage in military slang:

"I'm going to Ranger School, can you give me some G-2 ?"

Answer: "Yes, before you get there memorize every aspect of the operations order, be able to recite every paragraph and sub-paragraph from memory.

While you are at it you might as well learn the operations order in the context of squad and platoon level operations so you know how to conduct each of the main missions in FM7-8. If you really want to G2 the course, make up some laminated copies of each type Opord with blanks that you can use to quickly write details like grid coordinates and signal information in with a sharpie (fine point) or at worst case scenario with a grease pencil...oh yea, and take care of your feet."

Example in civillian usage:

"My owners manual says to program my remote I have to start by putting the key in the ignition 6 times.

However, the Pop-A-Lock guy gave me the G2 ...you just push and pull the key in and out of the ignition steadily until the immobilizer light on the dash illuminates. It worked like a charm."

This is my favorite term...as you can probably tell (thats some G2 for you).