Emily Dickinson Lexicon

RIG'ID, a. [Fr. rigide; It. and Sp. rigido; L. rigidus, from rigeo; Gr. ῥιγοω, to be stiff; ῥιγιος, stiff; whence L. frigeo, frigidus; Eth. ረገዐ raga, Heb. רגע, to be still, to be stiff or rigid. Class Rg, No. 3, 27. The primary sense is probably to strain or extend.]

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; 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.