ثَالِثٌ
1.
[Third]: feminine with ة. (T, &c.) The final ث in الثَّالِثُ is sometimes changed into ى. (M.) You say, هُوَ ثَالِثُ ثَلَاثَةٍ [He, or it, is the third of three]: thus you say when the two [terms] agree, each with the other; but not ثَالِثٌ ثَلَاثَةً; ثالث being regarded in the former case as though it were a subst.; for you do not mean to convey by it a verbal signification, but only mean that he, or it, is one of the three, or a portion of the three: (Fr, ISk, T, S:) and in like manner you say, هِىَ ثَالِثَةُ ثَلَاثَ [She is the third of three]; but when there is among the females a male, you say, هِىَ ثَالِثَةُ ثَلَاثَةٍ, making the masculine to predominate over the feminine (T.) When the two [terms] are different, you may make the former to govern the gen. case or to govern as a verb; saying, هُوَ رَابِعُ
ثَلَاثَةٍ or هُوَ رَابِعٌ ثَلَاثَةً, like as you say ضَارِبُ زَيْدٍ and ضَارِبٌ زَيْدًا; and thus you also say, هٰذَا ثَالِثُ
اثْنَيْنِ and هٰذَا ثَالِثٌ اثْنَيْنِ, meaning This makes two to be three, with himself, or itself. (ISk, T, * S. [In most copies of the S, for ثَالِثٌ اثْنَيْنِ is put ثَالِثَ اثْنَيْنِ; and, in the explanation of this phrase, ثَلَّثَ اثْنَيْنِ for ثَلَثَ اثْنَيْنِ: IB has remarked that these are mistakes.])
ثِلَاث occurs in the sense of ثَالِث in a tradition cited voce ثَانٍ in article ثنى. (Sh, T in article ثنى.)
2.
3.
[ثَالِثَ عَشَرَ and ثَالِثَةَ عَشْرَةَ, the former masculine and the latter feminine, meaning Thirteenth, are generally held to be indecl. in every case without the article; but with the article, most say in the nom. الثَّالِثُ عَشَرَ, accusative الثَّالِثَ عَشَرَ, and gen. الثَّالِثِ عَشَرَ; and in like manner in the feminine Accord. to some,] you say, هُوَ ثَالِثُ عَشَرَ as well as هُوَ ثَالِثَ عَشَرَ [He, or it, is a thirteenth]: he who uses the former phrase says that he means هُوَ ثَالِثُ ثَلَاثَةَ عَشَرَ, (T, S,) i. e. He, or it, is one of thirteen, (T,) and that he suppresses ثلاثه, and leaves ثالث decl. as it was; and he who uses the latter phrase says that he likewise means this, but that, suppressing ثلاثة, he gives its final vowel to the word ثالث, (T, S,) to show that there is a suppression: (S:) but IB says that the former of these two phrases is wrong; that the Koofees allow it, but that the Basrees disallow it, and pronounce it a mistake. (L.) [And according to J, one says, هٰذَا
الثَّالِثَ عَشَرَ and هٰذِهِ الثَّالِثَةَ عَشْرَةَ
This is the thirteenth, or this thirteenth: for he adds,] and you say, هذَا الحَادِى عَشَرَ and الثَّانِىَ عَشَرَ and so on to twenty [exclusive]; all with fet-h; for the reason which we have mentioned: and in like manner in the feminine, in which each of the two nouns is with ة. (S.) You say also, ثَالِثَ عَشَرَ
ثَلَاثَةَ عَشَرَ [The thirteenth of thirteen]; and so on to تَاسِعَ عَشَرَ تِسْعَةَ عَشَرَ: and in like manner in the feminine (I' AK p. 316.)