castellated nut
English edit
Etymology edit
Physically descriptive via a metaphor; called thus because the slots in the nut — the castellations — have a fancied resemblance to the battlements of a castle.
Noun edit
castellated nut (plural castellated nuts)
- A type of nut (internally threaded fastener) with castellations, typically to hold a retaining pin that is passed through a cross-drilled hole, such as a cotter pin.