investigational

adjective

in·​ves·​ti·​ga·​tion·​al in-ˌve-stə-ˈgā-sh(ə-)nəl 

1

: of or relating to investigation

investigational activities

2

: relating to or being a drug or medical procedure that is not approved for general use but is under investigation in clinical trials regarding its safety and efficacy

an investigational new drug

Examples of investigational in a Sentence

Recent Examples on the Web

Now, the pharmaceutical company is running investigational new drug experiments, studies required by the FDA to demonstrate the drug’s safety before researchers can begin a Phase I clinical trial. —Isabella Backman, Hartford Courant, 27 Jan. 2026

Arrowhead Pharmaceuticals announced that its investigational RNA interference therapeutic, in combination with Eli Lilly ’s tirzepatide, doubled weight loss, improved fat reduction, and increased lean muscle tissue. —Jeff Marks, CNBC, 6 Jan. 2026

This allows seriously ill patients to receive investigational drugs outside clinical trials if there are no other available options. —Mary Kekatos, ABC News, 22 Dec. 2025

What The Study Involves The current study aims to better understand how an investigational sleep medication might help those who struggle to fall asleep before midnight. —Alice Gibbs, MSNBC Newsweek, 10 Nov. 2025

Word History

First Known Use

1905, in the meaning defined at sense 1

Rhymes for investigational

• associational
• civilizational
• coeducational
• configurational
• consociational
• denominational
• improvisational
• organizational
• orientational
• preoperational
• representational
• aspirational