formalin

This is a water-based solution of formaldehyde that is used to stop decay and preserve biological material. You might come across it in a lab, where it helps keep tissue samples and whole specimens in good condition for study. It is also used in embalming to help preserve a dead body. Even though it is useful, it can be harmful, so it has to be handled with care.

Formalin is a water-based solution of formaldehyde, usually with a small amount of methanol added to keep the formaldehyde stable. It is best known as a preserving fluid used in medicine, biology, and embalming. Although it has important practical uses, it must be handled carefully because it is toxic and irritating.

One common use is in embalming, where it helps preserve human remains for burial, transport, or medical study. It is also widely used in laboratories and hospitals to fix tissue samples so their structure stays clear when they are examined under a microscope. Because of this, it is important in pathology, anatomy teaching, and scientific research.

It can also be used to preserve whole biological specimens, such as plants or animals kept for classroom or museum study. In some settings it has been used as a disinfectant or in manufacturing, though that is not the use most learners will meet first.

At the same time, it is not a harmless substance. Breathing it in or getting it on the skin can cause irritation, and long-term exposure to formaldehyde is linked to cancer risk. For that reason, people who work with it follow strict safety rules.

So, the word usually refers to a strong preserving liquid used to keep tissues, specimens, or bodies from breaking down too quickly. In everyday English, it often appears in medical, scientific, or forensic contexts.