ركو1 رَكَا (ISd, K,) [aor. ـْ inf. n. رَكْوٌ, (ISd, TA,) He dug, or excavated, (ISd, K, TA,) the ground, forming an oblong hollow. (ISd, TA.) b2:  He made, formed, or fashioned, in a suitable manner, a small watering-trough such as is termed مَرْكُوّ, (Az, TA,) or a watering-trough  [in an absolute sense]; as also ↓ اركى. (TA.) 4 أَرْكَوَ see what next precedes.رَكْوَةٌ (S, Mgh, Msb, K, &c.) and رِكْوَةٌ and رُكْوَةٌ, (K,) all well known, but the first is the most chaste, (MF,) A certain thing for water: (S:) it is [a small drinking-vessel] like a تَوْر, of leather; (ISd, TA;) a small drinking-vessel of skin: (Nh, TA:) or a small دَلْو [or bucket, generally of leather], (Mgh, Msb,) well known: (Msb:) all of these explanations have been strangely neglected by the author of the K: (TA:) pl. رِكَآءٌ (S, Mgh, Msb) and رَكَوَاتٌ; (S,) Msb;) the latter allowable. (Msb.) The prov. (S) صَارَتِ القَوْسُ رَكْوَةً [lit. The bow became a ركوة, app. meaning the bow became exchanged for a vessel such as is called ركوة, but see what follows,] is applied in relation to the retiring of good fortune, and reverse in the state of affairs. (S, K.) b2:  A small زَوْرَق [or skiff]. (ISd, K.) b3:  A رُقْعَة [or piece of cloth, or rag,] beneath the عَوَاصِر, (K,) which means three stones [with which grapes are pressed so as to force out the juice,] placed one above another: so in the M. (TA.) [Hence, accord. to the TK, the prov. above mentioned: but I see not why.] b4:  (assumed tropical:)  The فَلْهَم of a woman; i. e. her فَرْج [or vulva]: so in the copies of the K: but in the T, her قُلْفَة [i. e. the prepuce of the clitoris], on the authority of IAar; as being likened to the ركوة of water: (TA:) the pl. [app. in all its senses] is رِكَآءٌ and رَكَوَاتٌ [as above], (K,) or in the last sense رُكًى. (TA.) رَكِىٌّ: see what next follows, in two places.رَكِيَّةٌ A well: (S, Msb, K:) or a well containing water; (MA;) otherwise a well is not thus called: (Durrat el-Ghowwás, in De Sacy's  Chrest. Ar. ii. 332:) or a well not made neat; or not constructed [or cased] with bricks [&c.]: (MA:) pl. رَكَايَا (S, Msb, K) and ↓ رَكِىٌّ, (S, and so in some copies of the K,) or the former is the pl. and ↓ the latter is [properly speaking] a gen. n., [i. e. a coll. gen. n.,] and often occurs as a sing. and as a pl., (Nh, TA,) or the pl. is also رُكِىٌّ: (so in some copies of the K and in the TA:) accord. to ISd, it is from رَكَا in the first of the senses assigned to this verb above. (TA.) مَرْكُوٌّ [pass. part. n. of 1: b2:  and hence, as a subst.,] A large watering-trough or tank: (AA, T, S, K:) [in the S and K is added, وَالجُرْمُوزُ الصَّغِيرُ, which may mean either that the small watering-trough is called جرموز, and such is the case, or that مَرْكُوٌّ also signifies a small جرموز, agreeably with what here follows, and with an explanation of this word in the TA voce حَوِىٌّ:] Az, after mentioning AA's explanation given above, says, but what I have heard from the Arabs is, that the مركوّ is a small watering-trough or tank, which a man makes, or forms, or  fashions, in a suitable manner, with his hands, at the head of the well, when he has not, and cannot procure, a vessel in which to give water to a camel or to two camels: and that which is large is not thus called. (TA.) [But see an ex. voce سَلْسٌ.]