noun

• (botany, horticulture) A plant that grows larger and more rapidly than usual.
  "Evidence is accumulating that bolters are plants which have changed their long-day habit to that of short-day."
• (flour milling) A machine or mechanism that automatically sifts milled flour.
  "The bolter was basically a sheet or roll of wire mesh or cloth (most often canvas or linen, but sometimes silk or another fabric). The flour produced by the mill was fed through or over the device, which was shaken by a mechanism (several were possible) taking power from the drive train leading from the water wheel to the millstones."
• (petroleum refining) A filter mechanism.
  "This first bolter contains a screen of eight meshes to the inch and separates the hard particles, dirt or scale."
• (Australia, sports) An obscure athlete who wins an upset victory.
  "Last year he was eliminated by the bolter Jo-Wilfried Tsonga and this time he was beaten by the shining star, Fernando Verdasco."

verb

• (dialect) To smear or become smeared with a grimy substance.
  "Methinks I see them with their boltered hair, Staring and grinning in thy gentle face, And in their ruthless hands their daggers drawn,"
• (of a whale) To swim or turn sideways while eating.
  "Close observers of the habits of whales in more recent times however do not record this practice and it must be regarded as a fanciful belief which probably arose as Gunther (1949) suggests as a fisherman's explanation of the patches and their frequent association with boltering whales."
• (military, aviation) To miss a landing on an aircraft carrier by failing to catch the arresting gear wires with the aircraft's tailhook.
  "Commander Kleemann came back and boltered again on his second attempt. lt is unheard of for him to bolter twice in a row. Then on his third attempt he got aboard with an OK three-wire trap."