Definition of "colloid"

Glue-like; gelatinous.  examples

(chemistry) A stable system of two phases, one of which is dispersed in the other in the form of very small droplets or particles.  examples

(meteorology) An intimate mixture of two substances, one of which, called the dispersed phase (or colloid), is uniformly distributed in a finely divided state throughout the second substance, called the dispersion medium (or dispersing medium).

(geology) A particle less than 1 micron in diameter, following the Wentworth scale