What does flatwise mean?
Flatwise is a directional adverb meaning 'in a flat position' — that is, oriented so that an object's broad, flat face is horizontal rather than balanced on its narrow edge. The word belongs mostly to the vocabulary of woodworking, carpentry, and construction, where it carries real practical weight: a plank loaded flatwise resists bending far better than one set edgewise, and instructions for stacking, gluing, or fastening timber frequently specify flatwise placement. Formed by combining 'flat' with the old English '-wise' suffix, which means 'in the manner of', it sits alongside more familiar compounds such as 'clockwise', 'lengthwise', and 'likewise'. Though rarely encountered outside technical contexts, it is precise and unambiguous where vaguer phrases like 'lying flat' might not fully specify the orientation. For anyone working with boards, panels, or tiles, flatwise is a small word that does useful, exacting work.
adverbIn a flat position or orientation, especially with the flat face of an object (such as a board or plank) horizontal rather than on edge.
- Lying or placed with the flat surface horizontal, as opposed to on edge.
- (Less commonly) describing motion or impact occurring against a flat surface, as when something strikes flat rather than on an edge.
"Stack the boards flatwise so the shelves don't warp under the weight."
"The planks were stacked flatwise in the lumberyard to prevent bowing."
"She set the tiles flatwise on the workbench before applying the adhesive."
Flip a board from edgewise to flatwise and you've changed its load-bearing strength several times over — which is exactly why carpenters care about this humble little adverb.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of flatwise
Flatwise is formed from the adjective 'flat', which derives from Old Norse 'flatr', combined with the English adverbial suffix '-wise', from Old English 'wīse', meaning 'manner' or 'way'. This suffix has produced a family of direction- and manner-words such as 'lengthwise', 'crosswise', 'clockwise', and 'likewise'. Flatwise emerged as a technical term, appearing in trade and craft usage to describe the placement of boards and other objects, and remains in use chiefly within those domains today.
How flatwise is actually used
A technical, somewhat rare term found chiefly in woodworking, construction, and engineering descriptions, where the orientation of a board or panel genuinely matters to its strength and appearance. It is neutral in tone and understood in both British and American trade English, though general readers may be unfamiliar with it. It is occasionally used attributively in technical writing, but its standard role is adverbial.
Easily confused with flatwise
'Flatly' means in a dull, absolute, or unemotional manner (e.g. she refused flatly), whereas 'flatwise' describes the physical flat orientation of an object.
'Edgewise' means positioned on its narrow edge rather than its broad face, the opposite orientation to 'flatwise'.