Het - short for heterozygous. Means the animal carries ONE copy of a mutant gene.. if the gene is recessive, the animal will appear normal.. as in a het albino. HOMOZYGOUS means it carries TWO copies, and therefore will actually exhibit the trait (ie look albino)
Morph - hobby name for a genetic mutation that is bred for.. ie albino, or different colors/patterns.
Hypo - means 'less'. In the snake breeding world, it can mean 'hypomelanistic' or less black.. as melanin is the black pigment. There is also hypoerythristic (less red) and others.
Hypo is from the Greek and literally means "under" as in hypodermic "under the skin." It is commonly used to indicate less of something, or a reduction in color, activty, hormone levels, etc. Like Hypomelanistic, hypoactive (opposite of hyperactive), hypothyroid, hypoglycemic, etc.
Finally, all those years of studying ancient Greek pays off! Woo Hoo!