From Longman Dictionary of Contemporary Englishdropperdrop‧per /ˈdrɒpə $ ˈdrɑːpər/ noun [countable] TZa short glass tube with a hollow rubber part at one end, that you use to measure liquid one drop at a time
Examples from the Corpus
dropper• Folly was a dropper of things and a leaver around of other things.• A bait dropper, as opposed to a swimfeeder, has limitations.• The first Montblancs were filled by unscrewing the nib section and filling the barrel with an eye dropper.• I found a medicine dropper and used that to feed it the milk they left me.• They can easily become workaholics, name droppers, gossips and braggarts.• Avoid essential oils sold in bottles with a rubber-tipped dropper.• It comes with three prepared slides, three live specimen holders, ant house, water dropper and instructions. 