upstack

== English == === Etymology === From up- +‎ stack. === Noun === upstack (plural upstacks) The upper part of the stack. 1969, British Ceramic Society, Transactions, Volume 68 Ground particles are fed up the upstack where they circulate to the downstacks and either pass through outlets on the inner radial surfaces (if they are small enough) or are swept again to the bottom of the upstack by low-pressure inlets […] === Anagrams === stack up, stackup, tack-ups, tacks up