The word "zeta" refers to the sixth letter of the Greek alphabet. It is commonly used in mathematics to represent a certain mathematical value or as a variable in equations. Full definition
Silver particles in a low ionic environment develop a negative charge called zeta potential which causes the particles to behave as though they possess a negative charge. (silver-colloids.com)
They find a thick disk of dust that extends to within 2.5 AU of zeta Leporis. (sciencemag.org)
A flattened, disk - like structure with a semi-major axis of ~ 100 AU in size is detected around zeta ^ 2 Ret. (arxiv.org)