Colloid

Part of speech: noun

Pronunciation: /ˈkɒlɔɪd/

Definitions

1. A substance containing microscopic particles evenly distributed in a medium, where these particles remain suspended without settling and do not separate over time
2. A mixture where small particles are evenly distributed within a continuous phase, creating a uniform solution-like appearance while preventing sedimentation
3. A material made up of tiny particles dispersed throughout another substance, maintaining an even distribution without settling

Etymology: Thomas Graham, the Scottish chemist, gave "colloid" its name in 1861 after noticing that some substances, such as gum arabic and gelatin, would not pass through a parchment membrane the way salts did. He compared them to glue, a substance whose ancient Greek name was "kólla", and the new term was built on that comparison. The word was coined in French as "colloïde" and taken into English from there. The second half, "-oid", comes from the Greek "eidos", meaning "form" or "appearance", so "colloid" literally means "glue-like". The suffix is the same one found in words like "android" or "asteroid", which describe something that resembles a thing without being it. The name says more about the substance's behaviour than about its chemistry: it was a description of how the material looked and acted, not a claim about what it was made of.