Bifacially

Bifacially is the adverb form of bifacial. The term comes from Latin bi- meaning two and facies meaning face; in English it describes something performed, occurring, or oriented on, or affecting, two faces or sides.

In archaeology and lithic technology, "bifacially" is used to describe a core, tool, or blade that has been worked on both faces rather than just on one side. Bifacially flaked tools show flake removals on both faces, producing edge properties and lateral symmetry that distinguish them from unifacial tools. The technique is associated with various prehistoric tool traditions, including some Acheulean and Mousterian assemblages, though the specifics vary by culture.

Beyond archaeology, bifacial describes devices or designs that interact with two faces. In modern technology, "bifacial" is applied to solar modules capable of producing energy from both the front and back sides; "bifacially" can describe actions or design choices that engage or exploit both faces—for example, panels mounted to maximize dual-surface exposure, or surfaces engineered to function on both sides. In broader engineering contexts, "bifacial" may refer to coatings, glazings, or components that admit or affect material on two sides.

Usage notes: "Bifacially" is most common in technical or scholarly writing; it is less common in everyday language. The word emphasizes dual-sidedness rather than a change in the object's location or orientation.