This is what the Evolution book says, and it is followed by a list of base keywords.   
TL:DL Keywords match what items and abilities work with each other and which do not.  

 
Examples:
Specific Materials: If a print calls for “hooch”... not all brews are hooch so you would need one with the keyword “hooch” for the material match.
Regional Company Names: If an Augment says 'only usable on Helscape weapons', you can easily check if a weapon has the Helscape keyword.

Abilities: For instance, a threat with 'Undead', 'Horde', and 'Aberrant' as keywords - the NPCs would know to take damage from horde bane, undead bane, and 'all aberrant' effects.

Use: There are other keywords that are there to prevent confusion or misuse - like ‘Single-Use' as a keyword means that after it's used, it's destroyed. 'Reliable' as a keyword means it continues to provide its ability's function when broken (mostly used on certain armors).

As new prints, augments and benedictions come out, you will see new keywords roll out.  Some of the latest are:


Blueprint Keywords

Item Type Keywords

Generic, Resource, Armor, Bow, Firearm, Firearm-2H, Knucks, Melee-Small, Melee-Standard, Melee-2H, Melee-Florentine, Exotic, Thrown, Shield, Trap-String, Trap-Pressure, Trap-Container, Gizmo, Vehicle, Augment, Land-Vehicle, Air-Vehicle, Water-Vehicle, Room-Augment, Procedure, Benediction, Startup, Brew, Meal, Poison-Applied, Poison-Ingested

Company/Organization Keywords

OOPH, AA, Candlepin, Thempire, Slappi, SG, Moulen, Heavycraf, Toothpiq, Steelpaw, Freeiron, Bigol, GL, Paradigm, Mountain, OF, Daline, Helscape, GG, Sosweet, Red-Ledger

Effect Keywords

Single-Use, Psionic, Faith, Reliable, Dangerous, Overpower

Single-Use: Items that are expended after one use.

Psionic: Items that count as a psionic effect.

Faith: Items that count as a faith effect.

Reliable: Items that continue to work even when Broken.

Dangerous: The user of this item is not immune to its effects.

Overpower: If an effect used by this item is defended against with a skill, the user may spend 1 Mind to have it repeat with a call of “Overpower”. If defended against a second time, Overpower may not be used again. This keyword ability cannot be used with PFA abilities.

Threat Keywords

All threats will have at least one keyword as well, to define what affects them. The Threat Keywords aren’t intrinsic to blueprints/devices, but may be referenced in item abilities. 

THREAT KEYWORD LIST: Undead, Horde, Aberrant, Irradiated, Raider, Critter, Outsider, (All Lineage and Strain names are also Keywords)