رهف1 رَهُفَ, aor. ـُ inf. n. رَهَافَةٌ (JK, MA, K) and رَهَفٌ (JK, K) and رَهْفٌ, (TA,) It (a sword, K, or a thing [of any kind], JK, TA) was, or became, thin, and slender; (JK, K, TA;) it (a sword) was, or became, thin in the edge or point; (Ham p. 349;) it was, or became, sharp, or keen; contr. of كَلَّ. (MA.) A2:  رَهَفَهُ: see what next follows.4 ارهفهُ, (JK, S, K, &c.,) inf. n. إِرْهَافٌ; (Ham p. 93;) and ↓ رَهَفَهُ, aor. ـَ (K,) inf. n. رَهْفٌ; (TA;) He made it (a sword, S, K, &c., or a thing [of any kind], JK) thin, (S, MA, K,) or sharp or pointed; (JK, MA;) he made it (a sword) thin  in the edge or point; (Ham p. 93;) he made it sharp, or keen. (MA.) b2:  [Hence,] أَرْهَفْتَ عَلَيْنَا لِسَانَكَ (tropical:)  [Thou hast sharpened against us thy tongue]. (A, TA.) And أَرْهِفْ غَرْبَ ذِهْنِكَ لِمَاأَقولُ (tropical:)  [Sharpen the edge of thine intellect for what I say]. (A, TA.) رَهِيفٌ Thin; slender; (JK, TA;) applied in this sense to a sword; (TA;) and also to a neck: (ISh, TA in art. بتع:) or thin in the edge or point; applied to a sword: (Ham p. 349:) or sharp, or keen; thus applied: (JK, * MA:) but Az says that it is seldom used; ↓ مُرْهَفٌ being  used in its stead. (TA.) مُرْهَفٌ (JK, S, TA) and ↓ مَرْهُوفٌ (JK, TA) Made thin; (JK, S, TA;) applied to a sword, (S, TA,) or to an arrow: (JK:) and the former, [or each,] made sharp or pointed: (JK:) [or made thin in the edge or pointed: or made sharp or keen: see 4:] and see also رَهِيفٌ. b2:  أُذُنٌ مُرْهَفَةٌ (assumed tropical:)  A slender ear. (TA.) And خَصْرٌ مُرْهَفٌ (assumed tropical:)  A slender waist. (Ham p. 93.) And رَجُلٌ مُرْهَفُ الجِسْمِ (JK, TA) and ↓ البَدَنِ ↓ مَرْهُوفُ, but the former is the more common, (tropical:)  A man slender in the body. (TA.) b3:  فَرَسٌ مُرْهَفٌ (assumed tropical:)  A horse lank in the belly, having the ribs near together: which is a fault. (IDrd, K, TA.) مُرْهَفَةٌ [as a subst., or an epithet in which the quality of a subst. is predominant,] Swords; (Ham p. 93;) and so مُرْهَفَاتٌ: (S and TA in art. برد:) or swords made thin in the edge or point. (Ham p. 349.) One says مُرْهَفَاتٌ بَوَارِدُ Sharp, or cutting, swords: (TA in art. برد:) or slaying swords. (S in that art.) مَرْهُوفٌ: see مُرْهَفٌ, in two places.