Firm; stiff; unyielding; not pliant; not flexible.
- Not flexible or pliant; stiff.
- Not moving; fixed.
- 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).
- Scrupulously maintained or performed: rigid discipline. See Synonyms at stiff.