Entry 1 sense Webster, 1913 Reniform /(r?n"?-f?rm; 277)/ · Ren·i·form · IPA /ˈɹɛnəˌfɔɹm/ 01 a. Having the form or shape of a kidney; as, a reniform mineral; a reniform leaf. 1. Having the form or shape of a kidney; as, a reniform mineral; a reniform leaf.