In this work, a new multiband terahertz metamaterial absorber is designed and characterised by numerical simulation method. In addition, the utilisation of the proposed absorber as a sensor is also investigated. The dielectric and thickness sensing characteristics are analysed. The proposed multiband metamaterial absorber has the ability for utilising the terahertz region up to 2THz. According to the results, it is found that the proposed absorber is capable of sensing unknown materials and material thickness with any of its five absorption bands. The sensitivity of the proposed sensor is 6.57GHz/unit sensitivity for dielectric sensing and 7.66 GHz/$\mu$m for thickness sensing.