Akademik

rigid
adj.
1 not flexible; that cannot be bent (a rigid frame).
2 (of a person, conduct, etc.) inflexible, unbending, strict, harsh, punctilious (a rigid disciplinarian; rigid economy).
Derivatives:
rigidity n. rigidly adv. rigidness n.
Etymology: F rigide or L rigidus f. rigere be stiff

Useful english dictionary. 2012.