1. [adj]  of or pertaining to construction or architecture
2. [adj]  (geology) pertaining to the structure or movement of the earth's crust; "tectonic plates"; "tectonic valleys"

TECTONIC is a 8 letter word that starts with T.

1. \Tec*ton"ic\, a.
   1. (Biol.) Structural.
   
   2. (Geol. & Phys. Geog.) Of, pert. to, or designating, the
      rock structures and external forms resulting from the
      deformation of the earth's crust; as, tectonic arches or
      valleys.
   
   

2. \Tec*ton"ic\, a. [L. tectonicus, Gr. ?, fr. ?, ?, a
   carpenter, builder.]
   Of or pertaining to building or construction; architectural.