cistern
UK[ˈsɪstən]US[ˈsɪstərn]
n
A tank for storing water, especially one connected to a toilet or supplying taps.
n
An underground reservoir for storing rainwater.
Etymology
The word 'cistern' has a clear and logical journey from a general container to a specific water-storage vessel. It entered English from Old French, tracing back to the Latin 'cisterna', a term for an underground tank. This Latin word is built on 'cista', meaning a box or chest, which itself was borrowed from the Greek 'kistē', denoting a woven basket. Thus, the core semantic thread from an ancient woven basket, through a Roman chest, to a medieval underground tank, and finally to a modern water storage unit, consistently revolves around the concept of a receptacle or holding vessel.
Analysis
The entire word 'cistern' functions as a simplex unit. It is a loanword from Old French 'cisterne', which derived from Latin 'cisterna', an underground reservoir for water. 'Cisterna' itself is an agent noun from 'cista', meaning 'box' or 'chest', which originates from Greek 'kistē', a woven basket or container.
Examples
The old house collected rainwater in a stone cistern beneath the courtyard.
After the storm, the cistern was filled to the brim.
The toilet's cistern needed repairing as it kept running.