in situ

adverb or adjective

in si·​tu (ˌ)in-ˈsī-(ˌ)tü 

-ˈsi-,

-(ˌ)tyü 

 also  -ˈsē-,

-(ˌ)chü 

: in the natural or original position or place

an in situ cancer confined to the breast duct

Examples of in situ in a Sentence

Recent Examples on the Web

In fact, in situ observations performed by the Cassini spacecraft—which orbited Saturn for more than a dozen years—showed that in some places the rings were made of almost perfectly pure water ice. —Phil Plait, Scientific American, 17 July 2025

The dominant hydrous mineral in mare basalts—apatite and entrapped melt hosted by olivine and ilmenite—were carefully characterized using scanning electron microscopy (Extended Data Fig. 1 and Supplementary Figs. 1–3) for further in situ chemical and isotopic analysis of water. —Keith Cooper, Space.com, 16 July 2025

Below, the royal family in situ in the Royal Box, the Prince of Wales and Prince George boldly rocking the hatless-ness privilege. —Guy Martin, Forbes.com, 14 July 2025

With Moyes back, new owners in situ and the men’s team set to play in a new state-of-the-art stadium from next season, optimism has returned after years of decline. —Patrick Boyland, New York Times, 29 May 2025

Word History

Etymology

Latin, in position

First Known Use

1740, in the meaning defined above

Rhymes for in situ

• amadou
• avenue
• ballyhoo
• baraboo
• barbecue
• barbeque
• bugaboo
• cabildo
• caribou
• cockatoo
• detinue
• devalue

Kids Definition

in situ

adverb or adjective

in si·​tu (ˈ)in-ˈsī-t(y)ü 

-ˈsi-

: in the natural or original position

the cancer cells remained in situ

Etymology

Latin, "in position"

Medical Definition

in situ

adverb or adjective

in si·​tu

(ˈ)in-ˈsī-(ˌ)t(y)ü, -ˈsi- also -ˈsē-, -(ˌ)chü

: in the natural or original position or place

an in situ cancer confined to the breast duct

see carcinoma in situ