probe

A slender, flexible surgical instrument used to explore a wound or body cavity.

An electrode or other device that can be placed inside something to take and convey measurements.

A substance, such as DNA, that is radioactively labeled or otherwise marked and used to detect or identify another substance in a sample.

A space probe.

An exploratory action or expedition, especially one designed to investigate and obtain information on a remote or unknown region.

The act of exploring or searching with a device or instrument.

An investigation into unfamiliar matters or questionable activities; a penetrating inquiry: synonym: inquiry.