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

Injectable aesthetic use is considered off-label/investigational and potentially contra-approved (opposite of approved use). —Cindy Krischer Goodman, Sun Sentinel, 5 Mar. 2026

Further compounding the issue is the astronomical cost of investigational product of research, driven upward over decades by escalating evidentiary standards, increasingly complex trial designs, and entrenched operational inefficiencies. —Elise Felicione, STAT, 26 Feb. 2026

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

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

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