The word "arch-way" refers to a curved or semicircular opening formed by an arch or by a vault, typically in a wall or a ceiling. Its antonyms are words that denote either the absence of an arch or a linear or angular structure. For instance, words such as "straight", "angular", "linear", and "rectilinear" can be considered antonyms of "arch-way". Other antonyms may include words like "flat", "level", "even", and "plane", which connote a surface or structure that lacks curvature or bends. Similarly, words like "square", "boxy", and "cubic" describe structures that are characterized by sharp angles and corners, rather than curves and arches.