The correct spelling of the word "polycillin" is actually "penicillin". The pronunciation of the word is /pɛnɪˈsɪlɪn/, with the stress on the second syllable. The "c" in "polycillin" is actually a mistake or a misspelling, as the drug name comes from the scientific name of the Penicillium mold that produces the antibiotic compound. It is important to use the correct spelling of medication names to ensure proper prescribing and administration.