emplectum

from The Century Dictionary.

• noun In architecture, either of two kinds of masonry in use among the Greeks and Romans, and other peoples.
• noun That kind of masonry, much used in ancient fortification-walls, etc., in which the outside surfaces on both sides are formed of ashler laid in regular courses, and the inclosed space between them is filled in with rubble-work, cross-stones being usually placed at intervals, either in courses or as ties extending from face to face of the wall, and binding the whole together. The term is, however, a loose one, and can be applied to any sort of masonry of greater thickness than the width of a single block, and so laid that the wall is bound together by some regular alternation of blocks placed lengthwise and endwise. Sometimes erroneously written emplection.