Noah Webster
Rigid
RIG'ID, adjective [Gr. to be stiff; Latin frigeo, frigidus; Heb. to be still, to be stiff.]
1. Stiff; not pliant; not easily bent. It is applied to bodies or substances that are naturally soft or flexible, but not fluid. We never say, a rigid stone or rigid iron, nor do we say, rigid ice; but we say, an animal body or limb, when cold, is rigid rigid is then opposed to flexible, but expresses less than inflexible.
2. Strict in opinion, practice or discipline; severe in temper; opposed to lax or indulgent; as a rigid father or master; a rigid officer.
3. Strict; exact; as a rigid law or rule; rigid discipline; rigid criticism.
4. Severely just; as a rigid sentence or judgment.
5. Exactly according to the sentence or law; as rigid execution.