The term LAB can refer to four different crossword solutions: CHEM, DNA, METH, and TECH. CHEM stands for chemistry, which is the study of matter and its properties. DNA stands for deoxyribonucleic acid, which is a molecule that carries genetic information in living organisms. METH stands for methamphetamine, which is a highly addictive stimulant drug. Finally, TECH stands for technology, which is the application of scientific knowledge for practical purposes.