Originally a case form of a defective noun تَحْت (taḥt, “location that is below”); see the usage note. From the root ت ح ت (t ḥ t). Related to Hebrew תַּחַת, Ge'ez ታሕት (taḥt), Ugaritic 𐎚𐎈𐎚 (tḥt /taḥta/) and Classical Syriac ܬܰܚܬ.
Practice speaking and memorizing "تحت" and many other words and sentences in Arabic.