اِمَّاimmā
used twice in a sentence, meaning "either ... or". ﴿اِمَّا شَاكِرًا وَّاِمَّا كَفُوْرًا﴾ (Al-Insān 76:3)
اِمَّاimmā (اِنْin + mā): that is, if; the redundant (zāʾidah) mā conveys emphasis, and with this اِمَّاimmā the imperfect (muḍāriʿ) occurs with the heavy nūn (nūn thaqīlah). ﴿فَاِمَّا يَاْتِيَنَّكُمْ مِّنِّيْ هُدًي﴾ (Al-Baqarah 2:38)