The term 'EIGHT PREFIX' refers to words that begin with the prefix 'oct-', which is derived from the Latin word for EIGHT. The three solutions for this crossword are OCTA (4 letters), OCTO (4 letters), and OCT (3 letters). OCTA means 'EIGHT' and is used in scientific contexts, such as octahedron (a polyhedron with EIGHT faces). OCTO means 'EIGHT' and is used in everyday contexts, such as octopus (an EIGHT-armed sea creature). OCT is a shortened version of OCTO and is also used in everyday contexts.