rigid
adj.adj. stiff and difficult to bend or move. You also use it to describe rules or people that are very strict and do not change.
adj. unable to bend or be forced out of shape; not flexible. Often describes systems, rules, or attitudes that are strictly maintained and resistant to modification.
The metal bar is rigid and won't bend.
The airline maintains rigid safety protocols to ensure that every aircraft is checked thoroughly before takeoff.
In aviation engineering, certain components must remain rigid under extreme pressure, while others require a degree of elasticity to absorb the vibrations of flight.
From Middle English rigide, from Latin rigidus (“stiff”), from rigeō (“I am stiff”). Compare rigor. Merged with Middle English rigged, rygged, rugged (“upright like a spine, rigid”, literally “ridged”), from ridge + -ed.
Often precedes the noun it modifies or follows a linking verb like 'remain' or 'become'.