accommodation clip an add-on clip, not permanently affixed to the cap; many independent manufacturers offered such clips, as did a number of major penmakers
  account an extremely fine, firm nib suitable for account book entries
  adjustable nib a Wahl-Eversharp exclusive of the '30s: a slider atop the nib controls its flexibility
  Aerometric nearly foolproof Parker filler, introduced 1948 on the Parker 51, originally hyphenated as "Aero-Metric"; a form of squeeze-filler or thumb-filler with a specially-designed vented silver breather tube for extra resistance to pressure changes; in unhyphenated form, widely used by collectors to denote a squeeze-filler with a breather tube
  Arrow nib Parker nib with a bold arrow imprint, used for Vacumatics and as replacement nibs for Duofolds; some late-production Duofolds were sold with such nibs
  artist's nib Waterman's term for a long-tined, very flexible, and extremely fine-pointed nib, capable of wide line variation; the designation postdates Waterman's 1925 catalog, although similar nibs were offered from an earlier date without any special appelation
  aspergillum Holy water sprinkler; sometimes made in pen form
  Autograph Sheaffer's designation for pens and pencils with a solid 14K gold cap band, intended for a personalized engraving; since engraving was included in the purchase price, unengraved examples are relatively uncommon
  baby bottom used to describe the shape of a nib's tip, where the bottom inner edges of the slit are excessively rounded; some rounding will stop the tip's inner edges from catching, but too much will prevent ink from getting to the paper
  Bakelite often misapplied as a generic term for any old plastic; Bakelite was a specific material, not often used for pens due to its brittleness
  banana to bend, as happens to pens in hot display cases at sunny flea markets
  bbl barrel
  BCHR black chased hard rubber
  BF button-filler
  BHR black hard rubber
  "Big Four" a modern collector's term for Waterman, Parker, Sheaffer, and Wahl-Eversharp, which are, in the USA, the top-line vintage pens most commonly found
  blind cap piece at end of barrel that screws off, typically to reveal the filler underneath
  blow-filler a mouth-operated pneumatic filler: blowing into a hole at the end of the barrel to empty out the ink sac
  BP ballpoint
  brassing area of wear on gold filled or plated metal, where the underlying base metal (usually brass) becomes visible; with gold filled items, replating is usually not a satisfactory restoration option
  breather hole see vent hole
  breather tube a tube inserted into the back of the feed, essential for pump and bulb-fillers, but also used at times with squeeze, button, and lever-fillers
  bulb-filler a simple and efficient filling system, using a small bulb at the end of the barrel and a long breather tube extending the length of the barrel; air is pumped out by multiple squeezes of the bulb, and ink flows in
  "bullseye" jewel c. 1939 Vacumatic jewel consisting of an extension of the blind cap, expanded over the tassie ring; the jewel end resultingly shows concentric laminations rather than stripes under bright light
  button-filler a button at the end of the barrel is pressed, bending an internal spring & pressure bar assembly which compresses the ink sac; in British usage, also called a stud-filler; usually, the button is concealed beneath a removable, screw-off blind cap, but in the push-knob filler, the cap and button are integrated
  capillary-filler no moving parts: when dipped, the reservoir absorbs ink
  Cardinal Waterman's designation for its red hard rubber pens and pencils
  cartridge although first introduced in the late 19th century, ink cartridges were not widely used until the advent of plastic refills in the early 1950s; top-line fountain pens did not embrace the cartridge until the 1960s, and many still prefer to use their cartridge-filling pens with convertors
  casein milk-derived plastic, vulnerable to moisture; rarely used in American production, except as colored ends on hard rubber pens, more commonly used in the UK and Europe; also called Galalith
  celluloid first widely-manufactured synthetic plastic, made by plasticizing cellulose nitrate with camphor; dominant material for pen caps & barrels from the second half of the 1920s, able to be made in virtually any color or pattern
  chalk marks stenciled marks applied to factory-new pens, typically denoting model, price, and nib grade; easily removed by rubbing
  chasing patterns impressed into the surface of a pen or pencil, consisting of repeated lines of varying length; usually found applied to hard rubber, much less commonly to celluloid and colored hard rubber
  chatelaine suspension fitting attached to a woman's dress or belt; attached items could include pencils and pens
  Christmas tree feed see spearhead feed
  clip mark circumferential mark on a cap made by a loose top-mounted clip
  coin-filler early and uncommon self-filler, in which a slot in the barrel allows a coin to be pressed directly against the pressure bar; most examples are minor-brand, the notable exception being the very rare Waterman
  collector finned ink trap inside the hood of pens such as the Parker 51 and 61
  combo pen and pencil combinations have been around for a long time, but their main period of popularity was in the later 1920s and 1930s, chiefly in the United States
  cone cap slip-fit cap of cylindrical form, not to be confused with a taper cap; the term originated with Waterman, and refers to the slightly tapering internal profile of the cap, which wedges onto matching tapers at either end of the barrel, the cap's outside diameter being significantly greater than that of the barrel
  cork used for piston seals, safety seals, and many plunger-filler packing units, alone and in combination with rubber
  cracked ice distinctive Conway Stewart pattern of irregular black blocks separated by thin lines of silver
  crescent-filler Conklin's signature mechanism, in which a flat metal crescent protrudes from the barrel; after rotating a lock ring, the crescent is pressed, flattening the sac