The correct spelling of the word "instillator" is actually "atomizer." The word comes from the verb "atomize," which means to break up into small particles or atoms. The IPA phonetic transcription for the word atomizer is /ˈætəmaɪzər/. The first syllable is pronounced as "at" with the schwa sound in the second position. The second syllable is pronounced as "uh" with stress on the first syllable. The final syllable is pronounced as "zer" with a voiced "z" sound and an "er" ending.
A dropper.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.