Triangular-based pyramid

/tɹaɪˈanɡjʊləbˈeɪst pˈɪɹɐmˌɪd/

/tɹaɪˈænɡjʊlɚbˈeɪst pˈɪɹɐmˌɪd/

a three-dimensional geometric shape with a triangular base and triangular faces that meet at a common vertex or apex point