Definition of "cinching"

It says something about the girl's ability or luck in shaping and securing the tent that not once did it begin to fold or come loose from its cinchings to the raft.

2010, Dan Simmons, Endymion

Panic-stricken, he knew not what to do as he watched his restive horse back away from him, turn, and bolt from his increasingly menacing scent, his belongings torn from their saddle cinchings as the animal sped through the brush.

2014, T. C. Rypel, Gonji: A Hungering of Wolves, page 209