Entry 1 sense Webster, 1913 Rectangular /(r?k*t?n"g?*l?r)/ · Rec·tan·gu·lar · IPA /ɹɛkˈtæŋɡjəlɚ/ 01 a. Right-angled; having one or more angles of ninety degrees. 1. Right-angled; having one or more angles of ninety degrees.