Metallurgy. a conical knob, mounted on a rod, for stopping temporarily the flow of molten metal or slag from a blast furnace or cupola.
Origin
1875-80; perhaps special use of dial. bot (now obsolete) iron tool for marking sheep, itself special use of Middle Englishbotte (variant of bat1) shepherd's crook
British Dictionary definitions for bott
bot1
/bɒt/
noun
1.
the larva of a botfly, which typically develops inside the body of a horse, sheep, or man