Definition of "rigid" []

• Not flexible or pliant; stiff. (adjective)
• Not moving; fixed. (adjective)
• Marked by a lack of flexibility; rigorous and exacting: "We have watered down a rigid training . . . until we now have an educational diet in many of our public high schools that nourishes neither the classes nor the masses” ( Agnes Meyer). (adjective)
• Scrupulously maintained or performed: rigid discipline. See Synonyms at stiff. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Two full seconds passed before Myles spoke, his expression rigid."
• "On the basis of the fact that, unlike (9), (10) can serve to express two distinct counterfactual beliefs, Kripke (1972) hypothesizes that a proper name is what he calls a rigid designator."
• "But he said he will not make a decision on a matter like stem cells based on what he called a rigid, ideological approach."