counter-beamn.
Etymology: Previous versions of the OED give the stress as: ˈcounter-beam.
Printing.
1874 E. H. Knight Counter-beam (Printing), a beam connected to the platen by two or more rods [by] which the reciprocating motion is communicated to the platen.
This entry has not yet been fully updated (first published 1893; most recently modified version published online December 2020).