2.  The Watad, consisting of three letters, one of which is quiescent.  If the quiescent follows the two moved ones, the Watad is called majmu’ (collected or joined), as fa’u (=fa’uw), mafa (=mafah), ’ilun, and it corresponds to the classical Iambus (U — ).  If, on the contrary, the quiescent intervenes or separates between the two moved letters, as in fa’i ( = fah’i), latu (=lahtu), taf’i, the Watad is called mafruk (separated), and has its classical equivalent in the Trochee (- U)

3.  The Fasilah,[FN#451] containing four letters, i.e. three moved ones followed by a quiescent, and which, in fact, is only a shorter name for a Sabab sakil followed by a Sabab khafif, as mute + fa, or ’ala + tun, both of the measure of the classical Anapaest (U U -)

ii.  These three elements, the Sabab, Watad and Fasilah, combine further into feet Arkaan, pl. of Rukn, or Ajzaa, pl. of Juz, two words explained supra p. 236.  The technical terms by which the feet are named are derivatives of the root fa’l, to do, which, as the student will remember, serves in Arabic Grammar to form the Auzan or weights, in accordance with which words are derived from roots.  It consists of the three letters Fa (f), ’Ayn (’), Lam (l), and, like any other Arabic root, cannot strictly speaking be pronounced, for the introduction of any vowel-sound would make it cease to be a root and change it into an individual word.  The above fa’l, for instance, where the initial Fa is moved by Fathah (a), is the Infinitive or verbal noun, “to do,” “doing.”  If the ’Ayn also is moved by Fathah, we obtain fa’al, meaning in colloquial Arabic “he did” (the classical or literary form would be fa’ala).  Pronouncing the first letter with Zammah (u), the second with Kasrah (i), i.e., fu’il, we say “it was done” (classically fu’ila).  Many more forms are derived by prefixing, inserting or subjoining certain additional letters called Huruf al-Ziyadah (letters of increase) to the original radicals:  fa’il, for instance, with an Alif of prolongation in the first syllable, means “doer”; maf’ul (=maf’uwl), where the quiescent Fa is preceded by a fathated Mim (m), and the zammated ’Ayn followed by a lengthening Waw, means “done”; Mufa’alah, where, in addition to a prefixed and inserted letter, the feminine termination ah is subjoined after the Lam, means “to do a thing reciprocally.”  Since these and similar changes are with unvarying regularity applicable to all roots, the grammarians use the derivatives of Fa’l as model-forms for the corresponding derivations of any other root, whose letters are in this case called its Fa, ’Ayn and Lam.  From a root, e.g., which has Kaf (k) for its first letter or Fa, Ta (t) for its second letter or ’Aye, and Ba (b) for its third letter or Lam

          fa’l would be katb =to write, writing;
          fa’al would be katab =he wrote;
          fu’il would be kutib =it was written;
          fa’il would be katib =writer, scribe;
          maf’ul would be maktub=written, letter;
          mufa’alah would be mukatabah = to write reciprocally,
correspondence.