| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
| Abbreviation | Definition |
| #3 (or #7) | Refers to head design of a plow bolt |
| &NT | With nut |
| 18-8 | Stainless Steel with 18% Chrome and 8% Nickel |
| 2, 5 or 8 | Strength grade of a screw or nut |
| 2A (3A) | Class of thread fit for inch screws |
| 2B (3B) | Class of thread fit for inch nuts |
| 2H | Nut strength level designation (ASTM A194 Grade 2H Heavy Hex Nut) |
| 6G | Class of thread fit for metric screws |
| 6H | Class of thread fit for metric nuts |
| A325 | Heavy hex structural bolt (ASTM A325), similar to Grade 5 |
| A490 | Heavy hex structural bolt (ASTM A490), similar to Grade 8 |
| A574 | Strength grade for socket head cap screws (ASTM A574) |
| AISI | American Iron and Steel Institute, specifies chemical composition of steels |
| AN | Precedes a dimensional specification for aircraft fasteners developed by the Aeronautical Standards Group. |
| ANSI | American National Standards Institute |
| AS | Alloy steel |
| ASME | American Society of Mechanical Engineers |
| ASTM | Used before a standard number developed by the American Society for Testing and Materials group. |
| B |
When followed by a number (ex: B-90), indicates hardness measured on the Rockwell B Scale. Also an abbreviation for Boron. |
| Bake (Bake-Out) | Heat treat process used in plating to prevent Hydrogen embrittlement |
| Bevel | Style of washer (square with a taper) used with I beams |
| Belleville | Style of lock washer, also called conical spring washer |
| BHCS | Button head cap screw |
| BHN | Hardness measured with a Brinell Hardness Tester |
| BR | Brass |
| BS | British Standard |
| BSF | British Standard Fine |
| BSW | British Standard Whitworth |
| BT | Bolt (on drawings) |
| C |
When followed by a number (ex: C-35), indicates hardness measured on the Rockwell C Scale. Also an abbreviation for Carbon. |
| C/R | Cross recess drive (typically Phillips style), Also Chamfer/Radius |
| Cad | Cadmium plating |
| CAD | Computer Aided Design / Drafting |
| Cad/Wax | Cadmium plating with a topcoat of wax |
| CH | Case hardened (type of heat treatment) |
| CL | Class (Metric material/Strength specification) |
| COO | Country of Origin |
| CR | Chrome |
| CRES | Corrosion resistant steel (usually refer to 18-8 or 316 stainless steel) |
| CS (cs) | Carbon or Steel, Also Countersunk |
| CSS | Counter sunk screw (flat or oval head) |
| CT | Course Thread |
| DAC (Dac 320) | Dacromet coating (registered trademark of Coatings International) |
| D/C Nut | Double chambered nut (distinguished from washer faced) |
| D/E | Double ended stud |
| DIN | An abbreviation for Deutsches für Normung, the German standards body. In reference to fasteners, DIN indicates fasteners that conform to a specific metric standard (will be followed by the standard number). |
| Deltaseal | Magnigard coating (registered trademark of Magni Engineered Coatings) |
| Dorrltech | Magnigard coating (registered trademark of Magni Engineered Coatings) |
| Driseal | Pipe Thread (registered trademark of Parker Hannifin) |
| ET |
External thread |
| F | Fully threaded |
| FB | Flange Bolt |
| F436 | Hardened flat washer with dimensions per ASTM F436 |
| FH | Flat head |
| FHCS | Flat head cap screw |
| FIL | Fillister Head |
| FIM | Full indicator measurement |
| FIN | Finishing (washer) |
| Flng | Hex flange bolt or nut |
| FNDR | Fender (washer) |
| FT | Fine thread or Fully threaded |
| FW | Flat washer |
| G | Grade |
| galv | Galvanized, typically refers to Hot Dip Galvanized |
| Gr | Grade, refers to strength level of screw or nut (ex: Grade 2, Grade 8) |
| GV | Galvanized |
| HB | Hex bolt, Also hardness reading measured on the Brinell Scale |
| HCS | Hex cap screw, also high Carbon steel |
| HD | Head |
| H.D.G. | Hot dip galvanized |
| HHCS | Hex head cap screw, Also heavy hex cap screw |
| HHMB | Hex head machine bolt |
| HRB | Hardness measured on the Rockwell B scale |
| HRC | Hardness measured on the Rockwell C scale |
| H.T. | Heat treated |
| HWH | Hex washer head |
| HX | Hex |
| ID | Identification (usually refers to manufacturer logo) |
| IFI | Industrial Fastener Institute |
| IH | Indented head |
| in. | Inch |
| ISO | International Standards Organization |
| ISIR | Initial Sample Inspection Report |
| IT | Internal thread |
| J429 | SAE standard that specifies strength levels of screws |
| J995 | SAE standard that specifies strength levels of nuts |
| JMNT | Jam Nut |
| K | Shorthand for the number 1,000 |
| Keps | Nut with a permanently attached washer |
| Kips | 1,000 points |
| ksi | Thousands of pounds per square inch |
| LB (lb) | Lag bolt, Also weight in pounds |
| Lb | Body length on screws |
| LCS | Low Carbon steel |
| LH | Left hand thread |
| LW | Lock washer |
| M | Metric |
| MB | Machine bolt |
| Mfg | Manufacturer |
| mm | Millimeter |
| MS | Machine Screw |
| MSNT | Machine Screw Nut |
| MTR | Material Test Report |
| NC | Unified National Course Thread |
| NE (NU, NTE, NTU) | Designations that define the thickness of nylon insert lock nuts |
| NF | Unified National Fine Thread |
| Nom | Nominal (reference dimension) |
| NPT | National Tapered Pipe Thread |
| NT | Nut |
| OH | Oval head |
| OV | Oval head |
| P | Thread pitch, Also Phillips head |
| P/B | Plow bolt |
| PH | Phillips head |
| Phil. Or Ph Dr | Phillips drive |
| Phos (P & O) | Phosphate and oil coating (typically Zinc Phosphate and Oil) |
| Pl | Plain finish |
| P/N | Part number |
| PN | Pan head |
| Pozi Drive | Special cross recess (registered trademark of Camcar Textron) |
| PPAP | Production part approval process |
| psi | Pounds per square inch |
| PT | Partial thread |
| PZ | Pozi-drive style of cross recess |
| R | Radius |
| Rb (RB or HRB) | Hardness measured on the Rockwell B Scale |
| Rc (RC or HRC) | Hardness measured on the Rockwell C Scale |
| RD | Round head |
| RH | Round head, or Right hand thread |
| RT | Rolled threads |
| S | Slotted |
| S/S | Stainless steel |
| SAE |
Standard American Equivalent - Uses inches as unit of measure, as opposed to metric. Also: SAE Pattern (washers). These washers have a smaller inside diameter than USS pattern washers. Also: Society of Automotive Engineers Also: When used with washers, it means "small OD." Also: When used with screws or nuts, it means "fine thread." |
| SBR | Silicon bronze |
| SD |
Square drive |
| SEMS | A type of pre-made screw and washer assembly |
| SHCS | Socket head cap screw |
| SKT | Socket |
| SL | Slotted |
| Slot. | Slotted drive |
| SMS | Sheet metal screw |
| Sq. | Square. Can also refer to square head bolt or square nut. |
| SS | Stainless steel or Set Screw |
| St | Steel |
| Taptite | Special triangular thread forming screw (registered trademark of Reminc) |
| T.H. | Through hardened (type of heat treatment) |
| TIR | Total Indicator Reading |
| T/S | Tapping screw |
| Torx | 6 lobe drive (Torx Drive, registered trademark of Camcar Textron) |
| TPI | Threads per inch |
| TT (TR) | Taptite thread (registered trademark of Reminc), also called Tri-Roundular |
| TTH | Threaded to head |
| Type 1 (23, 25) | Special thread forming or cutting tapping screws |
| Type AB (F, T) | Special thread forming or cutting tapping screws |
| UNC | Unified National Coarse Thread |
| UNF | Unified National Fine Thread |
| UNR | Unified National Thread with radius root |
| UNRC | Unified National Coarse Thread with Radius Root (standard rolled thread form) |
| UNRF | Unified National Fine Thread with Radius Root (standard rolled thread form) |
| USS |
USS Pattern (washers). These washers have a larger outside diameter than SAE pattern washers. Also used to indicate US course thread. |
| UTS | Ultimate tensile strength |
| WAC | Width across corners |
| WAF | Width across flats |
| W/F | Washer faced (can refer to a nut or a cap screw) |
| Whitworth | British Thread Standard (not the same as UN threads) |
| WS | Wood screw |
| Y | Yellow chromate |
| YS | Yield Strength |
| Z | Zinc |
| Zn | Zinc, usually referencing zinc plating (assumed to be clear zinc with clear chromate) |
| Zn/C (ZC) | Zinc plating with clear chromate topcoat |
| Zn Phos | Zinc phosphate and Oil (same as Phos and Oil) |
| Zn/Wax | Zinc plating with a topcoat of wax |
| Zn/Y (ZY) | Zinc plating with yellow chromate topcoat |