Found in the Ragazzini-Zanichelli dictionary.

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Note added at 14 mins (2006-03-13 12:07:17 GMT)
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De Mauro online:

ròc|chio
s.m.
1 TS arch., in una colonna non monolitica, ciascuno degli elementi cilindrici che sovrapponendosi formano il fusto

Merriam-Webster online: DRUM
5 : something resembling a drum in shape: as a : a cylindrical machine or mechanical device or part

Maybe even "column drum". See here:
http://harpy.uccs.edu/greek/olympia.html
Fallen column drums from the peristyle

http://blog.arlt.co.uk/blog/Greekreligionandtemples/_archive...
This column drum clearly was abandoned because it split, but it's still got bulges of stone which were there for the crane grapple to engage with.