Learn how to say Icosahedra correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word icosahedron:
noun (plural icosahedra /-drə/ or icosahedrons)
a solid figure with twenty plane faces, especially equilateral triangular ones.
late 16th century: via late Latin from Greek eikosaedron, neuter (used as a noun) of eikosaedros ‘twenty-faced’