ˈzāˌmän, ˈzēmən- noun
Usage: usually capitalized Z
Etymology: after Pieter Zeeman died 1943 Dutch physicist
: a phenomenon that is observed in the emission spectrum when a source of radiation is placed in a magnetic field or observed in the absorption spectrum when an absorbing medium is placed in a magnetic field and that consists of the breaking of single spectral lines into three or more components which are polarized