The spelling of the word "colyseptic" may seem complicated, but it can be broken down using IPA phonetic transcription. The first syllable, "co-", is pronounced like "koh", while the second syllable, "-ly", is pronounced like "lee". The third syllable, "-sep-", is pronounced like "sehp", and the fourth syllable, "-tic", is pronounced like "tik". Together, the word is pronounced "koh-lee-sehp-tik". "Colyseptic" refers to something that kills bacteria or inhibits their growth, typically in the colon.
Antiseptic, preventing sepsis or putrefaction.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.