re·ta·ma I. \rə̇ˈtämə, rēˈ-, -tāmə\ Etymology: New Latin, from Spanish, shrub of the genus Genista, from Arabic ratam retem synonym of genista II. noun alsora·ta·ma\“\ (-s) 1. a.: jerusalem thorn 2 b.: paloverde 2.[American Spanish, retama, from Spanish, canary broom]: any of several yellow-flowered tropical American shrubs of the genus Cassia