Example:
"Once you have filled your eyedropper with blue ink, make sure you only add one or two drops to the fish tank - otherwise you might poison the fish" said the teacher to her biology students. 
The Noun Project
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CC: Attribution, Commercial Use
Regionalism:
Neutral
Regional variant:
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Full Expression:
Scientific Instruments: eye dropper
This hand-held device is used to measure out small quantities of liquid.