the Berasit Hebrew Dictionary

ארון

This word appears to be technical jargon for an object within the Tabernacle. Most of the occurences refer to this mysterious object generally known as “the ark of the covenant”.

However, it is also used (in Genesis 50:26) to refer to the coffin or sarcophagus that Joseph was buried in in Egypt, as well as for a box that was used to collect money from the citizens.

Essentially, it is a wooden box. Several descriptions anyway describe its measurements and the techniques of its manufacturing.

not to be confused with ahren

LexID 727