Ātāpin (adj.) [fr. ātāpa, cp. BSk. ātāpin Av. Ś i.233; ii. 194 = Divy 37; 618] ardént, zealous, strenuous, active D iii.58, 76 sq., 141 (+ sampajāna), 221, 276; M i.22, 56, 116, 207, 349; ii.11; iii.89, 128, 156; S 113, 117 sq., 140, 165; ii.21, 136 sq.; iii.73 sq.; iv.37, 48, 54, 218; v.165, 187, 213; A ii.13 sq.; iii 38, 100 sq.; iv. 29, 177 sq., 266 sq., 300, 457 sq.; v.343 sq.; Sn 926; Nd1 378; It 41, 42; Vbh 193 sq.; Miln 34, 366; Vism 3 (= viriyavā); DhA i.120; SnA 157, 503. -- Freq. in the formula of Arahantship "eko vūpakaṭṭho appamatto ātāpī pahitatto": see arahant II. B. See also satipaṭṭhāna. <-> Opp. anātāpin S ii.195 sq.; A ii.13; It 27 (+ anottappin).