方ほう錐すい形けいMeanings1nounregular pyramidA geometric term for a pyramid whose base is a regular polygon and whose apex is directly above the center of the base.方ほう錐すい形けいの体たい積せきを計けい算さんする公こう式しきを覚おぼえていますか。Do you remember the formula for calculating the volume of a regular pyramid?