1(often disapproving) (of rules, methods, etc.) very strict and difficult to change synonym inflexible The curriculum was too narrow and too rigid. His rigid adherence to the rules made him unpopular. [..]

early 15c., from Latin rigidus "hard, stiff, rough, severe," from rigere "be stiff," from PIE *reig- "stretch (tight), bind tightly, make fast" (source also of Old Irish [..]

a shape that can't be pushed to make a different shape. • a triangle is the only rigid polygon, so triangles are often used in construction.

stiff.

incapable of or resistant to bending; "a rigid strip of metal"; "a table made of rigid plastic"; "a palace guardsman stiff as a poker&a [..]

A frame or fork which does not have any built in mechanical suspension system. Conventional forks actually are designed to flex slightly over bumps, but they are still called "rigid" forks a [..]

(adj) incapable of or resistant to bending(adj) incapable of compromise or flexibility(adj) incapable of adapting or changing to meet circumstances(adj) designating an airship or dirigible having a fo [..]

austerus

An idealized concept meaning something which does not deform under loading. In fact, all objects deform under loading, but in modelling it can be useful to idealize very stiff objects as rigid.

Capable of keeping a given shape under pressure.