تحتتَحْت is the contr. of فَوْق: (Msb, K:) and التَّحْتُ [signifying The location that is beneath, below, or under,] is opposed to الفَوْقُ, and is used in relation to that which is separate from another thing; الأَسْفَلُ being used in relation to that which is united with [or a part of] another thing. (Kull.) Sometimes, (K,) تَحْت is an adv. n., (Msb, K,) having a vague signification, its meaning not being clear unless it is prefixed to another word, as in the phrase هٰذَا تَحْتَ هٰذَا [This is beneath, below, or under, this]. (Msb.) And sometimes, it is a simple noun; (K;) in which case, [not having the article ال,] it is indecl., with dammeh for its termination, (K, and I'Ak p. 204,) provided that the noun to which it should be prefixed is suppressed, and the meaning of this is intended to be understood, but not the word itself; (I'Ak ubi suprà;) as in مِنْ تَحْتُ [Beneath, below, or under]; (K;) and in the saying, أَقَبٌ مِنْ تَحْتُ عَرِيضٌ مِنْ عَلُ [Lean beneath; broad above]: otherwise, it is decl.; (I'Ak ibid.;) as in تَجْرِي مِنْ تَحْتِهَا الأَنْهَارُ [Rivers running beneath them]; (Kur ii. 23, &c.;) i.e., beneath their trees, (Bd, Jel,) and their pavilions. (Jel.) [You say also, فُلَانٌ تَحْتَ أَمْرِ فُلَانٍ (assumed tropical:)  Such a one is under the command, rule, or authority, of such a one. And فُلَانٌ تَحْتَهُ فُلَانَةُ (assumed tropical:)  Such a one has as his wife such a woman: see an ex. in a verse cited voce إِذَا. The dim. is ↓ تُحَيْت: you say, هٰدَا تُحَيْتَ هٰذَا, and مِنْ تُحَيْتِ هٰذَا, This is a little beneath, below, or under, this.] b2:  التَّحْتُ is also the sing. of التُّحُوتُ, (IAth, TA,) which latter [in the CK erroneously written التُّحُتُ] signifies The low, base, vile, or ignoble, persons. (A, IAth, K.) It is said in a trad., لَا تَقُومُ السَّاعَةُ حَتَّى تَظْهَرَ التُّحُوتُ وَ تَهْلِكَ الوُعُولُ, i. e. [The hour of resurrection will not come until] the low, or ignoble, persons [shall prevail], and the noble persons [shall perish]: (A, IAth, TA:) or, as some say, until the treasures that are beneath the earth appear. (TA.) And in another trad. it is said that among the signs of the resurrection shall be this: أَنْ يَعْلُو التُّحُوتُ الوُعُولَ That the weak of mankind shall have ascendency over the strong. (TA.) تَحْتَانِىٌّ [Of, or relating to, the location that is beneath, below, or under; inferior; lower;] rel. n. of تَحْت, like as فَوْقَانِىٌّ is of فَوْق: ا and ن being very often added in the rel. n. (TA.) [تُحَيْت dim. of تَحْت, q. v.]