castellated nut

== English == === Etymology === 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 === 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. ==== See also ==== crenellation