حسم

حُسُامٌ حسام A sword; because it cuts that upon which it comes: (Msb:) or a sharp sword; (S, K, TA;) and in the same sense applied to a [knife such as is termed] مُدْيَة: (TA:) and (so in the S, but in the K “ or ”) the edge of a sword, with which one strikes. (S, K.) ― -b2- لَيْلَةٌ حُسَامٌ A lasting night: (K:) or a night of lasting evil, especially. (TA.)