Word of the Day
20 July 2026
knuckle
nounManufacturing
A convex portion of a vessel's figure where a sudden change of shape occurs, as in a canal boat, where a nearly vertical side joins a nearly flat bottom.
Why this one
Named for the way a finger bends: the shape does not curve away gradually, it turns at a line. The same word carries into pressure vessel heads, where the knuckle radius between the dished crown and the straight flange is where stress concentrates.
In use
Watch your weld sequence along that knuckle, it wants to pull the plate in as it cools.
Written by our editors to show how the term is used, not a recorded quotation.Sources
- Definition sourceWiktionary