Casket is of uncertain origin; possibly a diminutive of cask, or from Old French cassette ('little box'), diminutive of casse ('case'), from Latin capsa ('box'). The historical trail runs through capsa in Latin. The history must be left partly open, preserving the uncertainty rather than forcing a single unsupported ancestry. Used as a noun, casket now means "a coffin; a small ornamental box for valuables", so the present definition can be read against the older forms and meanings. The same lexical family is also visible in related forms such as cask and case. That uncertainty is part of the entry: the safest account is the attested form and the limited comparisons preserved with it.