Collet
Collet turns up in 2 fields: machine shop, farming. Here is what it means to the people in each one.
Collet in machine shop
A slotted, tapered sleeve that squeezes evenly around a tool shank or bar stock to grip it accurately.
A precision sleeve with lengthwise slits and a tapered outside, drawn or pushed into a matching taper so it closes evenly on a tool or part. Collets grip with better concentricity and less marking than jaw chucks over a narrow size range. Common systems include R8 for knee mill spindles, ER for tool holders and 5C for lathe and fixture work.
"Run the half-inch endmill in an ER collet, not the drill chuck, it'll pull out and wreck the part."
Collet in farming
The exact transition zone between the root and the stem of a seedling.
The botanical boundary line on an embryonic plant where the downward-growing root system meets the upward-growing hypocotyl or stem. In many species, this zone is visually indistinct, but it marks a critical physiological shift in vascular tissue arrangement.
"If you plant the seedlings too deep and bury the collet in heavy wet soil, they'll likely rot."