Clear salty liquid that is secreted by the lachrymal gland of the eye to lubricate the surface between the eyeball and eyelid and to wash away irritants.
Source:
PAC, 2018, 90, 1121. 'Terminology of bioanalytical methods (IUPAC Recommendations 2018)' on page 1126 (https://doi.org/10.1515/pac-2016-1120)