Abstarct:   Terahertz absorbers have widespread applications in the fields of optoelectronic devices, detection, and sensing. In this thesis, we first define mextamaterials, terahertz, and graphene. Subsequently, building on previous research, we designed an absorber with a wide bandwidth and an absorption rate above 90%, which also exhibits low sensitivity to the angle of incidence. This makes it suitable for various applications such as imaging, sensing, and detection. To achieve such an absorber, we combined water and graphene to enhance absorption. Three proposed structures are introduced in this research. In the first proposed structure, an emoji design for graphene was used, resulting in a bandwidth absorption of 4.03 terahertz, highlighting the importance of incorporating a ring in the structure. In the second proposed structure, by modifying the absorber's design and using a cross pattern with a surrounding ring on graphene, the absorption rate reached 5.98 terahertz. In the third structure, a petal design with a ring and rectangular slits around it was used, increasing the absorption to 14.55 terahertz. This increased absorption was due to the resonances created between the petal, ring, and rectangular slits. The designed structures exhibit wide bandwidth and low sensitivity to polarization. In the third structure, which was specifically examined in more detail, it was found that this design maintains optimal performance for incidence angles θ from 0 to 55 degrees. These features make the proposed absorbers suitable for various THz applications such as detection, imaging, and other uses.