A synergy perk is a perk you get from having other perks. They can make up an unintended weakness between two perks, provide a bonus that makes sense, or provide a bonus for a build that would otherwise be ignored. Some examples;

Computer Whiz and Robotics Expert- Robotics Whiz- When sneaking behind robots you may now hack them to be temporary allies.

5 Intense Training- Impossibly Intense- Allows the player to have a max of 11 in SPECIAL scores.

10 Intense Training- BEYOND INTENSITY!- Allows the player to have a max of 15 in a SPECIAL score. Note: Since you can only have a max of 10 Intense Training this is more for the player to be able to use perks like Night Person and Solar Powered or purchase implants while already at 11.

Educated, Comprehension, and INT 6- Payed Attention In Class- Allows a max of 110 in a skill.

Night Person and Solar Powered- Ying and Yang- +2 Speech at night and +2 Energy Weapons in direct sunlight.

Strong Back, Scrounger, and Guns 30- Ammo for Days- Ammo weighs 50% less.

Adamantium Skeleton, Nerves of Steel, and Luck 7- Mithiral Man- Chance for normal attacks to become Deflected Attacks against you (a Deflected Attack is pretty much the opposite of Critical Damage).

Ok I think yall get what I am talking about. Do you think this should be included? All I want for Christmas is APA and a gauss rifle.

I don't like it. It would essentially create classes in a classless system, by added bonuses for getting various perks and/or traits together which would force characters to develop themselves along a specific tree for maximum effectiveness late game.

Besides, perks are already strong enough without a need to make them stronger.

http://fallout.wikia.com/wiki/Fallout_perks
http://fallout.wikia.com/wiki/Fallout_2_perks

Only because, looking at your examples, you're drawing your inspiration from the bastardized fallouts, which had perks that for the most part were meh.

These ideas seem borrowed from Bethesda's Fallout. Have you played the gamesas titles?