Define the word colloid

The word colloid, you may be interested to know, is derived from the Greek word "kolla" meaning "glue" and is defined as a system containing particles of size from one millimicron to 0.1 micron (10^-6 to 10^-4 mm).  Colloids are compounds with large molecular weights, which form dispersions  only with water. e.g. starch, proteins, glycogen, agar-agar. 

Crystalloids, on the other hand, are compounds with small molecular weights, which can form true solutions. e.g. sugars and amino acids.