(ف) ضَعَفَ يَضْعَفُ ضَعْفًاḍaʿafa yaḍʿafu ḍaʿfan: to increase something.
(ک) ضَعُفَ يَضْعُفُ ضَعَافَةًḍaʿufa yaḍʿufu ḍaʿāfatan: to be weak.
ضَعْفٌḍaʿf and ضُعْفٌḍuʿf (noun, ism dhāt): weakness.
ضَعِيْفٌḍaʿīf pl. ضِعَافٌḍiʿāf and ضُعَفَاءُḍuʿafāʾu (adjective on the pattern of فَعِيْلٌfaʿīl): weak.
اَضْعَفُaḍʿafu (elative, ism tafḍīl): weaker, weakest. ﴿وَخُلِقَ الْاِنْسَانُ ضَعِيْفًا﴾ (An-Nisāʾ 4:28); ﴿اَللّٰهُ الَّذِيْ خَلَقَكُمْ مِّنْ ضَعْفٍ﴾ (Ar-Rūm 30:54)
ضِعْفٌḍiʿf pl. اَضْعَافٌaḍʿāf: double or manifold (the singular ضِعْفٌḍiʿf is also used for the double, and its dual ضِعْفَيْنِḍiʿfayni also occurs).
Form IV (ifʿāl) اَضْعَفَ يُضْعِفُ اِضْعَافًاaḍʿafa yuḍʿifu iḍʿāfan: to increase, to multiply.
مُضْعِفٌmuḍʿif (active participle, ism fāʿil): one who multiplies. ﴿فَاُولٰٓئِكَ هُمُ الْمُضْعِفُوْنَ﴾ (Ar-Rūm 30:39)
Form III (mufāʿalah) ضَاعَفَ يُضَاعِفُ مُضَاعَفَةًḍāʿafa yuḍāʿifu muḍāʿafatan: to increase manifold, to multiply many times over. ﴿فَيُضٰعِفَهُۥ لَهُۥٓ اَضْعَافًا كَثِيْرَةً﴾ (Al-Baqarah 2:245)
Form X (istifʿāl) اِسْتَضْعَفَ يَسْتَضْعِفُ اِسْتِضْعَافًاistaḍʿafa yastaḍʿifu istiḍʿāfan: to consider someone weak.
مُسْتَضْعَفٌmustaḍʿaf (passive participle, ism mafʿūl): used as an adjective, deemed weak, i.e. weak, oppressed. ﴿اِنَّ الْقَوْمَ اسْتَضْعَفُوْنِيْ﴾ (Al-Aʿrāf 7:150)