isodiametric in British English
(ˌaɪsəʊˌdaɪəˈmɛtrɪk) or isodiametrical (ˌaɪsəʊˌdaɪəˈmɛtrɪkəl)
adjective1. having diameters of the same length
2. (of a crystal) having three equal axes
3. (of a cell or similar body) having a similar diameter in all planes