Ice

Ice is the solid form of water, formed at temperatures below 0 &deg;C. Comets consist mostly of ice. 

Ice can be used for medicinal purposes, notably to reduce swelling. 

It can also be used for cooling drinks such as martinis. 

An icicle is a spike of ice formed from the freezing and thawing of falling water. Intendant $𝜇$ once told Benjamin Sisko that she knew of Breen icicles were warmer than $𝜇$.