Rigorous

Definition

Rigorous is an adjective meaning (1) extremely thorough, exact, or accurate; (2) strict or demanding in standards, rules, or discipline; (3) harsh or severe in conditions; and (4) in mathematics, logic, or science, adhering precisely to formal principles or proofs.

Parts of Speech

• Adjective

Pronunciation

American English

• IPA: /ˈrɪɡərəs/
• Respelling: RIH-guh-russ

British English

• IPA: /ˈrɪɡ(ə)rəs/
• Respelling: RIH-guh-rəs

Etymology

Late Middle English: via Old French rigoreus (modern rigoureux) from Latin rīgōrōsus “stiff, severe,” from rīgōr “stiffness, severity.” Related to English rigor/rigour.

Derivatives

• rigor (US) / rigour (UK) (noun) — strictness; exactness; a high standard of accuracy
• rigorously (adverb) — in a rigorous manner
• rigorousness (noun) — the quality of being rigorous
• rigorism (noun) — a tendency toward strictness in moral or doctrinal matters

Synonyms

• thorough
• exacting
• stringent
• meticulous
• strict
• precise
• scrupulous
• exhaustive

Antonyms

• lax
• lenient
• casual
• slack
• inexact
• superficial

Usage

Adjective: “All materials underwent rigorous testing before release.” / “Admission standards are rigorous.” / “The expedition endured rigorous winter conditions.” / “Provide a rigorous mathematical proof, not just an example.”

Related Terms

• Methodology: A system of methods whose quality is judged by rigor and reproducibility.
• Robustness: Reliability of results under varied assumptions; often pursued alongside rigor.
• Verification/Validation: Processes that establish rigor in engineering and research.
• Proof: A formal demonstration ensuring mathematical rigor.
• Due diligence: Thorough review or investigation, emphasizing rigor.
• Rigor mortis: Physiological “rigor” meaning muscular stiffening after death (etymologically related).
• Contrast with vigorous: Vigorous means energetic or forceful; rigorous means strict or exact.

Detailed Definitions

Adjective

• Extremely thorough and accurate — emphasizing completeness and attention to detail.
  • Example: “A rigorous audit uncovered several inconsistencies.”
• Strict or demanding in standards — enforcing rules or quality criteria without compromise.
  • Example: “The lab maintains rigorous safety protocols.”
• Harsh or severe (of conditions) — physically or mentally challenging environments.
  • Example: “Training took place under rigorous desert heat.”
• (Mathematics/Logic/Science) Formally precise — following exact definitions, axioms, and proofs.
  • Example: “Provide a rigorous argument using epsilon–delta definitions.”